Sorry for this late response but I never had cause to search for this issue until now. I have the MP-60 and I too am experiencing a similar issue. If I have 10 blu-ray 4K Dolby Vision or HDR discs, 5 of them output normally in 4K. The others are downsampled to 1080p with no HDR, even though I previously never had an issue. It’s a handshake issue quite sure. I exchanged over a dozen emails already with OPPO and they are as baffled as I am. I also have a Sony - the A9G OLED. My next step is to contact Lyngdorf. Did you ever get your issue sorted out?