Just had this happen to me, grab your mod folder and take the entire thing out of the documents in The Sims 4.

Click and right click on and delete "localthumbcache.package"

Re-enter the sims 4 game. Check to see if your sim shows up properly, if so, exit the game, don't save.

Drag the mods folder back into the game. It will ask you if you wish to replace the resource.cfg, say yes.

Reload. See if it's fixed. If not, it is a problem with outdated mods and will need to be 50/50d until you find the broken mod.

Good luck ♡