Given that you've already tried resetting preferences, some more troubleshooting steps: 1. Disable the GPU by setting Preferences > Performance > Use Graphics Processor to Off. 2. Update your graphics driver by going directly to the manufacturer's web site rather than relying on Windows update: https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html#solution-4 [Use the blue reply button under the first post to ensure replies sort properly.]
Sounds like a candidate for resetting the preference file. Resetting the preference file is Adobe speak for deleating the preference file and then letting Lightroom Classic to recreate it.
The preference file can get corrupted, resulting in odd behavior. Some people have a knee jerk reaction in thinking they need to uninstall then reinstall Lightroom Classic, maybe that could be called for, but it would be better to first reset the preference file.
Be aware that resetting the preference file will result in Lightroom Classic creating a new catalog instead if opening your previously opened catalog (normally) so make sure you know where your catalog is.
Be aware the resetting the preference file will revert some settings in Preferences to defaults. So be aware of what you have changed, so that you can put those back the way you want them.