Priority Skipped Bug, Spring Leaf Drum
There is a bug that skips priority when opponent has a spell on the stack.
Steps to reproduce
You start your turn with Mountain, 2 Ornithopter, 1 Dire Flail, and Spring Leaf Drum. You activate Dire Flail ability targeting an Ornithopter. With ability on the stack, opponent casts Fatal Push on the Ornithopter.
Actual Arena behavior.
Arena skips your priority and resolves Fatal Push immediately.
Expected Arena behavior.
Arena should leave opponent's Fatal Push on the stack and give you priority. You should be able to activate the ability of your Spring Leaf Drum while opponent's Fatal Push is on the stack, to create 1 mana before the Fatal Push resolves.
The only work around is to play on full control at all times, which is not a good game experience for everyone.