Not entirely sure if this is a bug though I'm fairly sure it is.
When a pokemon returns from a rumble area where you can't resend it
back due to certain situations (ran out of certain maps/no longer
full moon etc), instead of showing the rest of the maps available
to resend back, it shows a blank screen.
This is often quite irritating as we will need to find the pokemon
I want to resend it from scratch, and I can see how irritating this
must be for users who are rumbling "moon maps" as they need to
re-select all 6 pokemons the next day due to this bug.