Change from xlsx to csv

JGG ,

I believe this is correct as the difference in connection strings would be found within the 'Transform Sample File from [your folder name]' query, as well as a different sample file being used for the 'Sample File' query, each in the new function group (automatically generated folder of queries).

Additionally, Windows tends to actually store .csv files as Excel csv, so may appear to Power BI as an Excel file when importing. You can see this from the icons that your .csv files display when viewing them in File Explorer - they will either show as an Excel icon or a text file icon.

Further to the above, if your .csv files are Excel csv (maybe even if they're not), you may need to select your 'Filtered hidden files' step in your output query and manually filter this table to only include files with [Extension] .csv to prevent all of your .xlsx and .csv files being bundled together during the transform function operation.

Your 'Filtered hidden files' step table should look something like this:

This is where you may need to filter rows to only include specific files in the folder for processing.

Pete