iATKOS | United Kingdom

I have looked everywhere and this is the last resort, apologies this goes against the rules but apple won't help.

Since upgrading to 10.15.4 my 4k display Asus PQ321Q won't work and just shows a black no signal screen. This monitor was working fine a few weeks ago in 10.15.3 4k@60hz but now the only way to get it to work is set it to SST at 30hz which is unsuable for me.

I tried updating to 10.15.5 beta and now went back and reinstalled clean to 10.15.3 but still nothing. Have tried resetting PRAM and SMC a few times but nothing. Thought maybe it's the Display port cable so tested a new one and still nothing. It's kind of ridiculous it's not working when it was fine before.

Works fine in windows with both cables (USB C - Displayport), so it's an OS X driver/software issue, holy crap it's been like 5 years with 4k monitors why can't Apple make this work...

AMD Radeon Pro 5500M 8 GB

Any ideas I can try even if I have to force kext or something? This is a common issue it seems and it's so stupid it's even an issue.

Thanks for any help!