I downloaded Photoshop 2021 last night and my Liquify tool no longer show images. It worked yesterday with my older version and now it does't. I've tried opening several images. All I get is this weird partial circle down in the lower right corner.
I'm on Windows 10. My Graphics Processor is checked in Performance and my Cache is set to 4.
This is not a fix but a possible work-around to keep you working. In case you didn't know, the Adobe Creative Cloud app allows for multiple versions of a single app to be installed simultaneously. You could possibly download and work with an earlier version while you sort this problem out on the current version.