Sometimes Power Queries generate errors. Some errors stop all data being returned and others will return a blank cell for the error in the returned table. You can list the rows that are generating the errors. This can help you identify what is causing the error.

I have manufactured an error in this data set.

I have changed the data type of the Test column to a date which generates two errors.

You can list the error rows by clicking on the blue 2 errors text next to the query on the right of screen.

This will open the Power Query window. It creates a new, separate query for the error rows.

A row number column is added to this error listing. This is the row number from the original data set. It displays all the error rows.

From this listing you can hopefully determine what is causing your errors.