Palettes is empty on Musescore 4.0

I was working along fine on a 4-part quartet piece. I saved continuously. Suddenly, with no obvious action, the palette is empty. It doesn't matter what score I open. There are categories, but they are all empty.

I restarted and nothing happened. How can I get them back. I'm using a brand-new laptop with windows 11.
Thanks in advance.