I don’t know if this is an issue with eg: Nvidia Drivers as haven’t had an Nvidia Card for sometime & never tested that B4.
Even try uninstalling and reinstalling your video card driver as sometimes that can fix glitchy things like that. Check you have the latest video drivers for your specific video card incase that might be the problem. I’ve tested EMC today on 3840x2160 res using a AMD RX580 8GB video card & Adrenaline 2020 drivers with latest Windows 10 (20H2) and EMC V8.1.979 everything works as normal.