I can confirm the issue. My Epheria Caravel has the same problem. I can Ram small monsters but not large monsters. Also, none of the cannon shots register any hits.
Seems like only some types of ships are having issues with hit registration. For example: Volante is fine (confirmed in Server chat, DarkHeart has one) but Caravel seems to be bugged.
Addition: I killed a bunch of small and large monsters with my matchlocks. That probably means the mobs themselves are fine. I think the ships are bugged out.