In getting to know the differences between shortcuts N, M vs Alt+N, Alt+M there appears to be some weird stuff going on. If I just use the Move commands (using Alt) I never have any problems. If I first use the Cross commands (no Alt) on a grand staff, this works but if I then use the Move commands on the same selection, the Move function ceases to work. I see some unpredictable behaviour e.g. rests flickering in upper or lower empty staves but the move is not made.
Is this a known bug? What is going on behind the scenes when using Cross vs Move?