I have been using power query for a few weeks now to merge about 30 workbooks into 1. They have about 5 tabs within each workbook. I am pulling tabs 1, 2, & 3 from the 30 different workbooks, but for some reason tab 1 is showing null/empty for all of the data. I have opened the workbooks to make sure tab 1 is not empty (and its NOT), and if i use the data from yesterday it works properly. What could the issue be? There were no changes in how the 30 different workbooks have been put together, so I dont see how this issue has become present, just as of today.
That's not clear do you check tabs by their order or by their names. Sheets "A and B" and "A and B" will be different ones since they have different names. If you change the name compare to previous time Power Query could work differently.
Also you may try to select not "First file" as the sample. but any other one.