I've experienced a bug with my Sephara brawl deck which hasn't happened before. I've had Sephara out and summoned Priest of Possibility. From his ETB he gained flying and vigilance. Noteably, the blue indestructible modifier was not showing up. This continued after applying additional modifiers to him via equipments. Finally, when i've attacked with it in combat, the enemy successfully destroyed him through blocking.

I've attached the relevant logs.