Issue with Left Anti Join - Type Text

Hey Anonymous - I'm not convinced the join has anything to do with it. Here is what could have happened:

1. You are converting some field to numerical of some sort (whole number, currency, percentage, whatever)
2. Way WAY below the 1,000 records Power Query uses for caching is a text value in that field.
3. When you do the merge and expand the table, now that record that might be record 30,000 is now record number 200. Now Power Query will try to convert it to a number and it breaks.

So look carefully at all numeric fields. 

A quick way to do this is to load both tables into Power BI as a test. That will load all records. Power BI will give you a good clean error on the numeric field with an alpha in it.

Or, you can try to use the Table.Profile() function on each table. Just wrap the last line of each table with Table.Profile() in the formula bar and wait. See if anything odd shows up.