I am having a problem with Excel / Power Query that I had once before back in 2018. The only solution that worked then was to re-image the hard disk.
The problem manifests itself in two ways:
1) When I open Power Query it is just white and the table does not show.
Cannot close the PQ pane with the X have to press Alt F4 twice.
Open PQ a second time and you can see the table of data.
2) When I try and do a merge the drop down selector for the second query is blank.
To do a merge I have to use the Advanced editor.
I have just had our IT dept completely uninstall O365 with a Registry clear out. The re-install.
Still had the same problem.
The fact that the only solution last time was a HD re-image makes me think that the problem is not in Excel / PQ itself. But it does not like something on my machine. Though nothing has been installed recently.
I have just installed the latest version of Office v2101 (build 13628.20274.