I have a macbook pro (15 inch, 2018, Radeon Pro 560X) to which I plug 2 external monitors: a LG 32UL950 4K over thunderbolt & an old ASUS full HD over HDMI.
The problem is when the ASUS is connected then the LG is only running at 30Hz.
When connected alone it’s fine at 60Hz.
This machine is supposed to support 4 4K@60Hz screens. Any idea how to fix this?
(I can’t confirm it but I think this issue started with one of the latest macOS updates, 11.3 or 11.4)
EDIT: Display preferences