I've recently started having problems with refresh-rate switching. I'm using PMP 1.3.11 (same problem with 1.3.10) on Windows 10.
My TV is set on 50 Hz, and PAL files run without issues. But, when I play a 24p or NTSC file, and refresh-rate switching kicks in, the screen turns black and nothing happens. The TV has switched to the correct mode, but PMP is no longer the active window - doesn't respond to remote or keyboard.
I have to ALT+TAB+Enter, to get back to PMP, and then the video starts playing correctly. When I stop the playback, the same thing happens again when PMP switches back to 50 Hz - black screen.
If I turn off Display Mode Switching, there are no problems. I'm not sure if this a PMP problem or a Windows problem. The refresh-rate switching worked fine a few weeks ago.
I've attached a log where I test 24p, PAL and NTSC files.