Cute and stupid game! So can each piece only be moved x times? I've had a few games where a piece could no longer be moved without any clear messaging as to why this occured.
I only hope there are MORE units and twists added! If it happens again I'll try to give you any relevant info.
A potential clue, at least one of the times it happened, when highlighting the stuck unit, I was getting the unit info of another unit somewhere else on the board.
Can multiple units share the same space?