[CURRENT ISSUE] Sims 4 already running

@fairyr0re  What antivirus do you use?  Some of them have extra settings that need to be adjusted.  And when you reset your user folder, did you ever try to play without adding anything to the new folder?  If not, please do so now and let me know whether it works.

You can also try playing in a new admin Windows account, as a test.  Make it a local account, as in, don't sign into Microsoft, and don't sync with any other services you normally use.  You'll be able to sign into your existing EA account and won't need to reinstall Sims 4, but your saves and other content won't be available.  That can be addressed later; for now, just let me know whether the game loads properly.

@Da_Anxiety_45  You can try the suggestions above as well.  But it's definitely not an issue that anyone at EA is working on; I don't know why that support rep would say it was.  This is always a system issue, with something blocking Sims 4's access to the user folder, so with the exception of adjusting to a new operating system or something similarly global, this is not the responsibility of EA to fix.

@madison00ulo  I've merged your post with another thread on the same issue.  Please try the suggestions in this article:

https://sims4.crinrict.com/eng/crin-error/game-already-running/

and then the other suggestions above.