When is a flat a flat?

If I create a note (say b) and then flat it by typing minus this creates a Bb as expected. If I then edit the note by typing option-up arrow and then option-down arrow this moves the note up a whole step (but shows it as a Cb but plays as a C natural), and then down a half step but still shows it as a Bb, but sounds as a B natural. So I have to type minus again which makes it a B natural and then minus again to get back to Bb.

What then heck is happening here? This is all very confusing!

It’s a bug, which will be fixed in the forthcoming 1.0.20 update. In the meantime you probably want to delete and reinput the note.