Data disappeared after expanding from Merging in PowerQuery

[duybachhpvn]

Hi,

I'm facing a very strange behaviour of PowerQuery that after expanding new columns from a merging operations, some of the data in existing columns disappear after the new expansion step.

I found a random fix online that when I add an Index Column right before the expansion step, then the disappearance of data in existing columns is resolved. 

However, I dont understand why an expansion of a merge step can make data disappear like this? This is the case that I find the issue before any trouble, but if PowerBI just randomly delete data in existing columns, I find it hard to control the data integrity...

Illustration as below:

Below image is the step before expansion

Below image is the disappearance of data in column "Revised Package Type" and the 2nd last column after expansion

Then, if I add an index column right before the expansion step, then I dont have that issue

Thank you

[Jimmy801 · Accepted solution]

Hello @duybachhpvn 

you could try on your first expand step to add a Table.Buffer like this

Table.ExpandTableColumn(Table.Buffer(#"Filtered Rows1"),........

If this post helps or solves your problem, please mark it as solution (to help other users find useful content and to acknowledge the work of users that helped you)
Kudoes are nice too

Have fun

Jimmy

[duybachhpvn]

Hi,

It seem to work for me now. But why was data disappearing  without this Table.Buffer?