CAS X to delete Sims isn't working

Hey everyone, I've been having this problem for a while now. The little "x" over a Sim's head on CAS on the bottom left to delete them isn't functioning. I've tried clicking around it, it just won't work. Here's what I've tried already:

• Running game without Mods and CC
• Deleting localthumbcache.package
• Repairing game

Does anyone have any ideas on how to fix this and/or what it could be?