Yes, I already did all of that. I found out the problem, I enabled 10 bit color on AMD Adrenalin which caused HDR to be disabled.
Hi,  I just recently purchased a Dell G3223Q which states it is HDR600 capable. But when I tried to turn it on in the settings, it says HDR isn't supported. I tried running DxDiag and it says it isn't supported either. 
G3223Q, HDR not supported?