I believed unchecking the symbols does allow you to remove their registration, but I’ve never had to uninstall them to check. I’m installing a fresh set now to try it out.
Though to answer your other question, yes the engine has some caches that can be regenerated, and that was my next recommendation, but I’d also recommend backing them up first, in case this causes another issue. Since DDC is mostly shaders, it will cause a shader rebuild.
The DerivedDataCache and Intermediate folders.
