Go to properties, and change its speed.
Expected result: clip shrinks or enlarges accordingly.
Actual result: clip disappears.
Undo brings it back into view.
On further testing,
if I add a second Mp4 video to track 2, then carry out steps 2 and 3 above, it works as expected.
Also, works fine if a colour clip is added instead of a video.
ALSO - this also works as expected:
Place a video on V1
Cut it anywhere (S)
Press Undo
Change speed in properties.
Works as expected.
The bug only seems to appear when the video is imported to the timeline and nothing is changed on the timeline… ?
This bug I reproduced appeared in version 24.02 and happens when Settings > Timeline > Automatically Add Tracks is turned on. Changing a clip’s properties was sensitive to the current track (gold background) as opposed to which track the clip is on. So, the workaround is simple: change the current track to be correct before changing Properties (anything, not just speed).
This is fixed for the next version 24.06