What I did: Create a new note, then press Cmd + Option + Up to collapse the new note.
What happened: The note fails to collapse when this key combination is pressed.
What I expected: That the note would collapse. 
Things that might be helpful to know (Agenda version, OS and model, etc): The opposite keybinding (Cmd + Option + Down) does actually collapse the note, so the bindings are temporarily reversed. Also, the bug only arises a handful of times after the note is created, after which the keybindings work exactly as expected.