After updating to 11.1 external 4K Monitor is no longer working over 1080p

I have a LG 43 UN 700B 4K HDR Monitor. But after the latest update to big sur 11.1 its no longer possible to use 4K Resolution... even with SwitchResX the resolution is unavailable....

I restarted and plug / unplug the monitor already several times but it will not work...

Somebody else had a similiar problem?