I was playing a battle on showdown(gen 8 ag) and my Crobat used fly against the opposing Machamp. the Machamp had a flame orb so it had guts. It used Facade and to my surprise, it landed on my Crobat even though it was in the air. Remember, it had flame orb so it must of had guts. How did the facade hit?
All moves used by or against a Pokémon with this Ability cannot miss. It also allows Pokémon to be hit during the semi-invulnerable turn of Fly, Bounce, Dive, Dig, Shadow Force, Sky Drop, and Phantom Force.
Source The Machamp had probably No Guard, which allowed to hit your Crobat in air. Hope this helps!