Ok understood
a) I looked at your symptom screenshot. Is the source content 2d or 3d? Im having major dramas myself with 3d playback on powerdvd software. I can however do 2d movies just fine from bluray disc to say h264 MKV encoded stuff on UHD@60hz. Can you post a sample so I can see if I replicate too? Does it happen on any type of film encoding or container forma or does it happen only on specific typest? e.g. MP4, MKV, H265, HEVC, VC-1, MPEG2 etcetc
b) When you say problems in UHD above 30hz, do you mean the actual refresh rate of the display above 30hz or do you mean video content at higher frame rates than 30 FPS, say high motion 60 FPS films?
c) I was in the same case as you with my HDMI 2 display ports for my UHD display. Each of the ports are HDMI 2. However I was not until I carefully read the manual which is hundred pages plus did I actually discover that despite all ports being HDMI 2, some of them dont support certain features. Like only one port does ARC, one port does 60 hz with high colour gamut etcetc. I wouldnt be suprised if yours is the same and you need to change the port your using. Read the manual thoroughly.