I already posted this in the Desktop forum, but didn't seem to get any answers. I'm fairly certain it's a bug so I'm reposting here.
I'm having an issue (Sept 2017 release) where certain values have unexpected case changes after going through LEFT or Query Editor's Split Column function. The odd part is that the preview of the split column is correct, but the final result (after applying the change) is incorrect. An example:
Original Data is a direct import of some sample IDs from an Excel sheet. I imported this into a brand new PowerBI project, nothing else inside.
Split Column is what I see inside Query Editor when I split the column at 15 chars. This is what I see beforeI hit "Close & Apply". This data is correct - the results are case-sensitive and unique as expected.
Final Split is what I see in the tableafterI hit "Close & Apply". This data is incorrect - there are now several non-unique IDs as a result of the uppercase/lowercase change.