What were you doing before bug occurred: sailin’
Steps to reproduce: when marines come after you and they board off their ship to attack you, their ship will no longer take damage from cannons (didnt test damage from player). note that the marines were never attacked by player moves, they boarded off automatically once they were in the vicinity of the player. because of this, players cannot obtain the sealed chests by first sinking the ship then killing the marines. 
F9 Logs ( press f9 to view them in-game): dont have
Pictures/Videos: ship bug