Okay, but why would almost clicking the arrow next to Documents close Playlists, but not the 2 other open sections? Why would one need to be so absolutely precise to exactly hit the arrow to make it "work", and why does it not behave like this during the other times I almost hit the arrow, but missed.
To me, this is obviously not correct behavior.
Clicking on Documents (or the arrow next to it) should expand or collapse that one item, not something else. If the idea is to have clicking on the bar collapse everything but what you click, but clicking the arrow collapse only that thing, okay. Weird and not at all intuitive, but okay. But even if so, that is not what is happening.
I'm confident what is happening should not be happening, but if you feel that clicking on one item should collapse one (and only one) other item, and not affect what was clicked, then I guess all is working properly.
Either way, thank you for having a look. Have an excellent day.