When you are on a item of the collection, you expect it to expend (to see the children) with the right arrow and to collapse with the left one. It's not the case here. Reproducible: Always
Olivier, I moved this to the shortcuts, I currently don't have access to my Linux machine so I can't test (waiting for a new fan and cooler for my laptop), but if this is really a bug (code present for the action rather than not implemented), leave it here. Else, this should be moved to the wishlist.
I think it was working in the 2.8 (but I can't test that for now)
Thank you for reporting this bug in KDE software. As it has been a while since this issue was reported, can we please ask you to see if you can reproduce the issue with a recent software version? If you can reproduce the issue, please change the status to "CONFIRMED" when replying. Thank you!
Closed because Amarok is not used or maintained