How to stop powerbi from auto-resizing columns

Just wondering if you still have this issue?

The issue is the Column Header in the bottom table. Since the column header is blank in the bottom table, and there is no data in the column itself in the second table either, it shrinks the column accordingly; whereas, if you had either data or a column header, it would auto-fit to the longest one. That is why it retains the width on the top table.

The workaround for this is to add text that is the length of the same column in the top table into the column header in the second table and make the text the same color as the header background (effectively hiding the text in the header background, so it looks blank, but actually has text there). That should resize the column to the correct width to match the one in the top table. (Of course if you have the top table set to auto-fit, if the data in the top table is ever changed to longer lengths than the longest one now, you will have to adjust the bottom table header by adding text accordingly to the column header to accommodate that change in the top table).

Hopefully this is something fixed in future versions of Power BI, but this is the simplest workaround I have found.

Hope this helps.