If you're working from an expanded board view (where multiple sub-boards are shown together) or from a workspace view (individual files without any board context), Air can’t tell which board an item originally came from. Since items might live in more than one sub-board, moves from these views aren’t supported.
To move items out of one board and into another, open the specific board they’re in, not the expanded parent view. From there, Air can correctly process the move.
Organize your workspace like a pro! Check out our Organze Content collection in the help center to learn about all the ways to keep your workspace functional and easy to manage.