Hi, this is something new, because I used to do this frequently, please test to see if you get the same.
1.) Import a video onto a new track
2.) Ctrl-F2 and click "Ignore audio"
3.) Duplicate item (Ctrl-D, or copy/paste, no difference)
4.) Now hit F2 and try to click reverse
For me, it's greyed out. When I choose "Reverse items as new take" I get to see why. It notes, "Reverse item not supported for MIDI, will open copy in the midi editor to reverse there"
This is not a MIDI item, it's just an item with no audio. If I duplicate before ignoring audio, I can reverse, but then if I ignore audio on the reversed take, then duplicate, it shows the Reverse checkbox ticked, but greyed out.
Definitely was doing this a lot last year to get smooth looping ambient videos, not sure what changed.
This has been confirmed by not me over here, I just copy/pasted entire post to the bug report board:
https://forum.cockos.com/showthread.php?t=260552
I'm using a ThinkPad t430 running Windows 8.1 64bit architecture, latest version of Reaper.