I am having the same problem since the August 2025 update. I was playing with mods but my game would just send me to the world selection screen. I did the 50/50 method until I could load into my game. I couldn't interact with anything at all so I decided to uninstall all mods and see if I could interact. I could not, so I started a new game, no mods, no scripts, no cc. Took out my entire mods folder. Still didn't let me do anything. I deleted the localthumb cache and avatar cache, even the game version file as I found a forum that recommended it. I repaired the game, didn't fix. Restarted my computer, updated it, still same problem. I uninstalled the game, reinstalled it, still same problem. Changed my graphics settings to laptop mode thinking that might help. Nothing. I have a 2017 school laptop so no Direct X 11 so I turned that new setting to disabled instead of automatic. Didn't change a thing.
I can open the game, use the new game and load game screens no problem. I can even mess around by evicting sims, opening the gallery, randomizing traits and name on a new sim, and the free realestate cheat works too. I load into my game and wait for all the ui to light up. (Like how you need to wait for the game to finish loading and it's all greyed out.) My mouse cursor stays as the pointer and never changes. I cannot click on anything in the game, only ui around the borders. Shift clicking does not change the cursor or give me any options either. I can save my game, go out to the map and back, but I cannot click on a single thing in game. No sim, no mailbox, no ground. My sim was standing around and another one came up to him to talk and they attempted a conversation but she just kept walking and despawned. My sim was still stuck in conversation mode (swinging arms and talking) for awhile after. She never stopped on her walk, never came up to my sim. I've been trouble shooting for over a week now and I honestly just wish I could go back to the last version and play in airplane mode and just wait it out. I want my sims.
Oh, the event is happening right now too. It only loaded the very last time I booted up my game after I reinstalled the whole thing. The quests finally popped up. I can use those menus no problem.