Why can't I place a sphere static mesh?

Ok, so I’m trying to place a sphere static mesh in my project, but whenever I try to place one, it just shows me this, and I can’t place it. I have no idea what “gumball” is (I’m assuming it’s an older material that i deleted a while back), so how do I get rid of it? I’ve tried deleting and reinstalling unreal engine, as well as restarting the application, but nothing works, it’s still there! Help!