A clean reinstall fixed it for me. I had to uninstall twice because I noticed the EA App didn’t remove all of the folders for Sims 3. I’m not sure if this is how it is for everyone, but my Sims 3 has its designated download directory (I chose a specific drive but it usually goes on the C drive automatically) where the game and bin files are, then in a separate location (my documents folder) it has its other directory where my mods, downloads, savedsims, etc is. When I uninstalled the first time it didn’t remove the documents folder directory so when I reinstalled it, it wasn’t a clean fresh install; it recognized that folder and didn’t reset it. After I deleted that and made sure both directories were deleted after an uninstall, the new install was completely from scratch and I put back the important files (saved sims, library, userprefs, mods, game saves, etc). I have so much CC and not enough patience so I did the not recommended method of putting all the hundreds of downloads into the folder and installing via the launcher at once. I’d freshly redownloaded my store content earlier so i knew those files were good and not bugged with the box icon. I opened a save with a lot of CC and store content in use and had no errors. Yay!
The only issue I had was Hidden Springs, but a fresh download from the direct store page (not the purchase history page, that one was giving me a bad download for Hidden Springs) fixed the box error and everything is back to how it was. Monte Vista and Lucky Palms didn’t have any problem like Hidden Springs did.
I think this is probably an issue that came from the transition of origin app to the EA app. Maybe something in that document folder that might have been leftover from origin didn’t mesh with the store content? If anyones having trouble definitely make sure the EA App uninstalled everything.