2 abysses in map did not close

i uncovered this whole map and especially checked the areas around these 2 open abysses, but couldn't find any more abyss mobs. i'm not sure if those 20 mobs remaining are elsewhere on the map, i didn't double check the whole map, but i did uncover the whole thing, so it's possible those 20 mobs are from these abysses and spawned off screen. the map had a powerful boss, and i used an abyssal tablet. neither the map nor the tablet had any mods that affect abysses, the closest to that being increased desecrated currency on the tablet.