I believe I have the same issue!
I realised that my Sims 4 game was being saved to my OneDrive, despite me not asking it to, and that everything was going there, rather than a folder on my PC as per the good old days, when I kept getting messages that I was deleting a load of files from there. Turns out they were the Sims 4 files I had been trying to transfer from my old PC and the Origin system over to the EA app on my new PC...
All in all, seems like a massive pain - don't really get why there's no option to change where your game file gets saved to???
