If I move an issue to the last positioned column in Task Board, but the transition for such movement is not defined, I get an screen with the
check box "Set remaining estimate to 0 hours" but without any available transitions.
I think in case there is not available transitions the standard screen has to appear ->
"Sorry, no transitions were found!
Are you meeting all the workflow step conditions?
If so you might want to verify your Task Board mapping"

There is not point to see an empty screen that ask me "Set remaining estimate to 0 hours" and I can't go the anywhere from there.