[simpucker]

Despite the fact that I had Windows Update disabled, it somehow forced me to update and lo and behold, I encountered the issue with refresh rate and blank screen. After an hour or so of trying different things it seems that I have sorted it. Maybe this helps someone:

1. Installed the very latest Intel driver (I have i3-6300T)
2. Display mode: Fullscreen #1
3. Use fullscreen window: No (this was the key for me, after disabling this, it started working reliably)
4. Blank other displays: No
5. Adjust display refresh rate: Start/Stop or Always (both work)

Works for me. Disabling full screen mode did the trick for me. Now, switching between 50 fps and 60 fps and/or 59.94 fps material works like it should: My physical display changes its refresh rate so that the playback looks smooth, and the picture returns within a few seconds, i.e. I am not required to tab out of Kodi, which has been a painful workaround since the Windows Fall update.

To compensate for the fact that my display now takes a few seconds to adjust its refresh rate, I have enabled an intentional start playback delay (system settings --> delay after change of refresh rate).

For the record: Intel graphics solution here, too.

By the way, I never had this blank screen problem when running multiple displys in the first place. It was only when running a single display (external projector via HDMI) that I encountered the blank screen not returning problem. Again, disabling full screen mode fixed this.

Thanks a lot!