What is your operating system? Windows 10
What is your Shotcut version? 24.01.28
Loop > Selection doesn’t work when:
The selected clip is the last one in the Timeline.
If the selected clip is alone in the Timeline.
I noticed this: When you choose Loop all, the blue loop bar doesn’t go quite to the end of the timeline. It stops 1 frame before the end.
When you choose Loop Selection this 1 empty frame in the blue bar isn’t there.
It seems that the loop feature needs this empty frame to work properly.
By the way, we have the same problem when using Loop Marker on a range marker that is at the end of the last clip in the timeline.