Forum Discussion
Mege Table Issue
When I tried to merge queries,the merge with dropdown is blank. As you can see in this screenshot.
Hi HasnainNB
Here are the most common causes + fixes (in order of likelihood):
1) The other “tables” are not actually tables in Power Query
The Merge dropdown only lists queries that return a table. If a query returns a list / record / scalar / parameter, it won’t appear.
Check:
- Click each query on the left and confirm the preview shows a table with columns.
- If you see List, Record, or a single value → that query won’t show up.
Fix:
- Convert it to a table (Transform → To Table) or adjust the query to output a table.
2) Query preview is failing (so PQ can’t load candidates)
If any query has an error in preview or step evaluation, Power Query sometimes fails to populate the merge list.
Check:
- Look for queries showing Error in the preview pane or in the status bar.
- Check Applied Steps for error icons.
Fix:
- Resolve the error OR temporarily disable the failing step(s).
- Then try Merge again.
3) You’re inside a query context that limits what can be merged
Sometimes you’re editing a query that’s a function, parameter, or connection-only staging query and the merge UI behaves oddly.
Fix:
- Try merging from a “normal” query that clearly loads a table (e.g., one of your Lookup tables).
- Or duplicate the query (Right click → Duplicate) and try merging in the duplicate.
4) Privacy / firewall settings blocking combining data sources
Power Query can block combining sources depending on privacy levels (“Formula.Firewall”), and the UI can get weird.
Fix (quick test):
- File → Options and settings → Options
- Privacy: set to Ignore the Privacy Levels (temporarily, just to test)
- Or set both sources to the same privacy level (Organizational)
If it suddenly works, it’s a privacy/firewall configuration issue.
5) Power Query cache/UI glitch
This happens more than people expect.
Fix:
- Close Power Query Editor
- File → Options and settings → Options → Data Load → Clear cache
- Reopen PBIX / workbook
- Try again
Also try toggling:
- Options → Data Load → “Allow data preview to download in the background” (turn OFF, restart)
6) Data source is fine, but columns aren’t loaded yet
If the preview hasn’t fully loaded or is stalled, the merge dialog can show blank.
Fix:
- Click Refresh Preview on the query you’re merging from.
- Wait for preview to fully load.
Retry Merge.
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This usually happens when Power Query can’t render the preview of the second table, not because Merge itself is broken.
Most common causes (check in this order):
Table has an error in earlier steps
Open the other query directly and make sure it loads rows without errors (red “Error” values).The query returns zero rows at preview time
For example:
Filter step removes all rows
Parameter-driven query with no default value
Merge dropdown will appear blank if there’s nothing to preview.
Query depends on another query that’s disabled or broken
If the target query references another query that fails, Merge can’t show it.Data source privacy / credentials issue
Go to Data source settings → make sure credentials are valid and privacy levels are not blocking evaluation.
8 Replies
Hi HasnainNB
Here are the most common causes + fixes (in order of likelihood):
1) The other “tables” are not actually tables in Power Query
The Merge dropdown only lists queries that return a table. If a query returns a list / record / scalar / parameter, it won’t appear.
Check:
- Click each query on the left and confirm the preview shows a table with columns.
- If you see List, Record, or a single value → that query won’t show up.
Fix:
- Convert it to a table (Transform → To Table) or adjust the query to output a table.
2) Query preview is failing (so PQ can’t load candidates)
If any query has an error in preview or step evaluation, Power Query sometimes fails to populate the merge list.
Check:
- Look for queries showing Error in the preview pane or in the status bar.
- Check Applied Steps for error icons.
Fix:
- Resolve the error OR temporarily disable the failing step(s).
- Then try Merge again.
3) You’re inside a query context that limits what can be merged
Sometimes you’re editing a query that’s a function, parameter, or connection-only staging query and the merge UI behaves oddly.
Fix:
- Try merging from a “normal” query that clearly loads a table (e.g., one of your Lookup tables).
- Or duplicate the query (Right click → Duplicate) and try merging in the duplicate.
4) Privacy / firewall settings blocking combining data sources
Power Query can block combining sources depending on privacy levels (“Formula.Firewall”), and the UI can get weird.
Fix (quick test):
- File → Options and settings → Options
- Privacy: set to Ignore the Privacy Levels (temporarily, just to test)
- Or set both sources to the same privacy level (Organizational)
If it suddenly works, it’s a privacy/firewall configuration issue.
5) Power Query cache/UI glitch
This happens more than people expect.
Fix:
- Close Power Query Editor
- File → Options and settings → Options → Data Load → Clear cache
- Reopen PBIX / workbook
- Try again
Also try toggling:
- Options → Data Load → “Allow data preview to download in the background” (turn OFF, restart)
6) Data source is fine, but columns aren’t loaded yet
If the preview hasn’t fully loaded or is stalled, the merge dialog can show blank.
Fix:
- Click Refresh Preview on the query you’re merging from.
- Wait for preview to fully load.
Retry Merge.
Did I answer your question? Mark my post as a solution! Appreciate your Kudos !!
This usually happens when Power Query can’t render the preview of the second table, not because Merge itself is broken.
Most common causes (check in this order):
Table has an error in earlier steps
Open the other query directly and make sure it loads rows without errors (red “Error” values).The query returns zero rows at preview time
For example:
Filter step removes all rows
Parameter-driven query with no default value
Merge dropdown will appear blank if there’s nothing to preview.
Query depends on another query that’s disabled or broken
If the target query references another query that fails, Merge can’t show it.Data source privacy / credentials issue
Go to Data source settings → make sure credentials are valid and privacy levels are not blocking evaluation.
Hi,
Your Power Query UI looks a bit different from mine on the far right. I can still see 'Azure machine learning' and 'Text Analytics' which are both retired from Power Query or Power BI Desktop.
My own assumption is this would be a UI glitch from old version and i would suggest updating your Power BI to the latest version to give it another try.
Hey, HasnainNB ,
On why this happens, check responses from others; however, I think it's valuable to also know an extremely simple workaround and learn some M on the way. It's gonna allow you to also merge steps inside a single query.
The clicking merge will output these two steps:
= Table.NestedJoin(table1, {"column1"}, table2, {"column1"}, "newMergeColumn", JoinKind.LeftOuter //type of join)You can simply click add step button and write it yourself and define it for your needs:
If you want to use more columns to construct a key, you just add them to the list like this {"col1", "col2"}, on each side.
Tables are basically also steps (that return a table), so you can simply reference inner steps inside a query to join stuff together.
Hi! HasnainNB
Please try to refresh all queries and ensure that other tables have the headers to be used for merge. Also try using this in the latest version of Power BI desktop as suggested by others.
It usualy caused when the other queries lead to an error, but in your case, it seems it is not the issue.
Hi HasnainNB,
Thank you for reaching out to the Microsoft Fabric Community Forum. Also, thanks to Omid_Motamedise, AnkitKukreja, MasonMA, vojtechsima, for those inputs on this thread.Has your issue been resolved? If the response provided by the community member Omid_Motamedise, AnkitKukreja, MasonMA, vojtechsima, addressed your query, could you please confirm? It helps us ensure that the solutions provided are effective and beneficial for everyone.
Hope this helps clarify things and let me know what you find after giving these steps a try happy to help you investigate this further.
Thank you for using the Microsoft Community Forum.Hi HasnainNB,
Just wanted to follow up. If the shared guidance worked for you, that’s wonderful hopefully it also helps others looking for similar answers. If there’s anything else you'd like to explore or clarify, don’t hesitate to reach out.Thank you.
