Go to the help icon in the top right, go to Support and Diagnostics, and go to 'Clear cache data'[sic].
This is a longer unedited 2 minute video.

This fixed the problem for me. I mean the blank Data Panel comes back when the program is restarted, but at least I know what to click to fix things.
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One support person helped me a little bit a couple of weeks ago.

Then some Fusion 360 posts said it might be graphic drivers maybe, and I just had to stop there.

I did do a reinstall (tried Repair), but it looks like clearing the cache is enough.
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This is the short Fusion 360 post that had the answer:
https://forums.autodesk.com/t5/fusion...
I did a reply at the bottom to say that it worked for me.
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