Updated to Mac OS 11.3 and second external monitor no longer works...

[JanB]

Originally Posted by Tazovsky

4K is broken on 11.3. I needed to downgrade to 11.2.3 to make it work again

For me downgrade is not an option.

I use a resolution switcher (RDM - https://github.com/avibrazil/RDM) which gives me a workaround for the missing resolutions (but no HiDPI > 1080).

Works fine on a MacBook Air M1 with LG 4k Monitor connected via DisplayLink Dock.