I noticed that it has been a while since I last posted on this thread. Since this posting, a few things have changed in my setup, which may be worth sharing.
First, my previous, expensive, Dell monitor was retired, on account of Dell's lack of support and service, shameful. I then decided to install the new LG 32UL750-W monitor, which features a VESA DisplayHDR 600 screen. After that, PowerDVD worked with all its features, and I am still on version 21. Funny that this monitor produces an exemplary film picture inside Windows, but I had to delve into the NVidia control panel to adjust a few settings, nothing much complicated.
Windows does not support, as far as I can tell, Dolby Vision, but the user can play the discs with that codec in any UHD standalone player with HDR10, and the same HDR10 playback is supported in Windows.
Second, my old faithful LG WH16NS40 drive had its days numbered, when the open/close switch started to fail, and I could not find a single repair shop to replace it. So, I had to import the same drive again, and as a result I faced the same locked firmware, which prevents users to even read UHD Blu-Rays. This issue was sorted out by using Leawo's UHD drive tool, which replaced the firmware fairly quickly.