Ramsters show a vertical range when placing them, but will never deliberately attack an air unit (though they will damage air units that bumble into their line of fire when shooting at other units). May be the underlying cause of this bug, due to Betsy being partially aerial.
Either the vertical range shown is incorrect, or the Ramster's inability to fire on air units is incorrect.
Reproduction Steps:
Note when reproducing: You must keep other ground enemies outside of the Ramster's range, and ensure that the flier does not approach ground level - too low, and the Ramster may 'confuse' it for a ground unit and fire anyway. Make sure that the Ramster must use its alleged vertical range.
Screenshot - note that the Ramster has a vertical range line.
seems unbalanced... Because let's compare ramsters and PDT. PDT cost less DU, way longer range, poison tick + poison tick shard, cover both air and ground. So why would anyone use ramsters? It's the same with abyss lords walls: squire walls are cheaper, take less dmg, cover more ground (and with upcoming update even more ground when abyss lords stay u changed) so why would anyone consider abyss lords walls. It seems like building abyss lord is just like waisting DU on just ok defenses and offenses. I think you guys should rethink it - or give some kinda advantage for this extra DU spent over other alternatives - after all this game is all about finding the most efficient and optimal defense for DU at hand.
I've also encountered issue with this on Liferoot Forest. The aerial units will fly along the lane and then drop alitutde to attck the barrier blocking them, but the two ramster units I had behind the barrier did not attack them.