Apex says it's in fullscreen mode but is actually in borderless

Apex says it's in fullscreen in video settings but my mouse is able to cross over to my second monitor and I'm experiencing severe micro-stuttering that didn't occur a few days ago when I actually was in fullscreen. No matter what I've tried Apex will not go into fullscreen.  I tried Alt+Enter, I tried adding "=fullscreen" to the advanced launch options, and tried making a custom resolution in nvidia control panel (as per the instruction of this post: FIX for Apex not going true full screen : r/apexlegends) but nothing worked. Help me please!