abyss pits won't open

Bug Report ID: #918526790

This has happened several times, an abyss pit fails to open despite clearing out all enemies nearby, or even after completing a map showing "0 monsters remain".

I have experienced this issue a few times.
The overlay map will display a sort of counter for the remaining monsters.
My assumption is, any monsters killed outside of the Abyss zone, will not count towards the remaining monster counter resulting in failure to meet the threshold.
Not sure if this was intended.