Did you purchase anything recently? What you could do is sort your Official/Onestore folder by date descending, and look for what are the newest folders. Maybe an MP purchase is causing issues?
What you could do is something short of a full install. If you have the disk space, move a folder(s) out of that location. When the sim starts, and is depended on for starting, the sim will prompt to install this, just like it does a sim update.
If you have the time/energy to do it, it wouldn’t hurt to do one of, if not the, largest folder, which I think is called “fs-base”. Going along the lines of this being an interface issue of some kind, there are some folders that will have “ui” in their name. Moving those out might be worth a shot as well.
I say “move” because if the sim doesn’t prompt to re-install them as it should, then you can always move them back again. But only move folders in/out when the sim isn’t running.