I'm encountering a strange problem: I cannot execute any tools in QGIS (e.g., buffer, join--literally everything anything in the Vector or Raster menus. This seems to apply to all tools in all plug-ins, including the QGIS tools, GDAL, Grass, and Saga. I can see the tool options, but clicking one (e.g., Vector > Geoprocessing Tools > Buffer) deselects QGIS. It looks as if another window is opening but I am unable to see it or interact with it.
This error is happening 3.10.4, but also occurred in version 3.8 and 3.12. I have uninstalled and re-installed QGIS numerous times, and have deleted all leftover files in Program Files in between installs. The last build where QGIS worked as normal was version 3.8.