I eventually figured this out by starting a new game. The issue resolved when I used a repeat rune instead of just listing out all the moves. Still, it's a bug that the copter doesn't always disappear when it reaches the end of the level. Unfortunately I haven't been able to reproduce the error on my new save file.
Oh, so it getting stuck there is a bug...
I had the same issue! Solving the puzzle with repeat loops or not didn't matter, it was stuck until restarting the app completely. (Did not need to start a New Game!) Maybe something wasn't resetting correctly after the first few attempts while I was initially writing my spell?