I think I discovered a new problem with Rosegarden 12.10. 

I wanted to repeat a recorded MIDI segment, so I did what I used to do to accomplish that, namely, select the segment, and from the "Segment" menu, chose "Toggle Repeat". 

To my surprise, it had no effect.  I tried using the looping-button of the transport window, and that didn't work either. 

So I copied the segment, and pasted it several times (each time at the end), which accomplished what I was trying to do. 

But to my surprise, after I had more than one segment in the piece, I could select the last segment, and the "Toggle Repeat" segment menu entry worked. 

So why didn't it work for me the first time, I wondered. 

I clicked the "New" toolbar button (to make a new piece, and pasted the copied segment there (so it was the only one), but I was able to successfully toggle the repeat on it - no problems. 

So I exited from Rosegarden, and fired it up again.  I then recorded a short segment, then selected it and tried the toggle-repeat.  This time (as happened to me originally), nothing happened (it didn't work). 

I then (with the pencil tool) clicked on another track to create a short, empty segment. 

I then went back to the segment in track one, selected it, and tried the toggle-repeat.  This time, it worked (it repeated the segment to the end of the piece). 

So apparently, the toggle repeat won't work on the first segment initially (after application start) recorded into track 1.  But after you create a new segment (even in a different track), the toggle-repeat will then work on the original segment in track 1.