@thelostdreamss
Only a couple of other things I can suggest"
1. Delete the localthumbcache file and repair again. Then restart. Try the household where you found the problem. Then try another household to figure out if the problem is with the sim or a bigger issue involving other sims. You might try several households just to be thorough. If it works for some sims and not others, then you may have a glitched sim.
2. Create a new save in the same user folder and see if it works. If it does, that means there is probably something in the save that is glitched. Your choice to keep playing it or start a new one.
3. If it doesn't, then do a user folder (The Sims 4) reset. To do so, rename "The Sims 4" folder or move it out of the Electronic Arts folder. Start the game and go through making and replacing the required sim, then test to see if the create a date works, then save and quit. That will create a new user folder. Copy the saves folder from the old user folder to the new one. Start the game and test to see if it works now. If it does, then you quit without saving. Then put your mods folder in and test again to make sure it wasn't a mod that caused it. If a user folder reset doesn't work, then cause is probably in the save.
Hope this helps.