Make sure all your BillboardGuis aren’t set to infinite max distance, only set them to what they need to be
I had left a lot of BillboardGuis on infinite MaxDistance (because I’d use magnitude checks to disable and enable the UI in them) and disable/enable the BillboardUI itself.
What’s weird though is that Roblox still renders / draws BillboardGuis even when they’re disabled 
So to get rid of the problem, again, make sure your BillboardGuis are not set to infinite max distance unless absolutely needed