Server constantly crashes when more than one player enters.
I have noticed that this also happens with vanilla mobs too.

[ { "mob": "nmcmobs:mermaid", "persecond": 0.2, "attempts": 2, "amount": { "minimum": 2, "maximum": 5, "groupdistance": 3 }, "conditions": { "dimension": "minecraft:overworld", "inwater": true, "minheight": 10, "maxheight": 50, "maxthis": 20 } }, { "mob": "nmcmobs:merman_soldier", "persecond": 0.2, "attempts": 2, "amount": { "minimum": 2, "maximum": 5, "groupdistance": 3 }, "conditions": { "dimension": "minecraft:overworld", "inwater": true, "minheight": 10, "maxheight": 50, "maxthis": 20 } } ]

crash-2022-11-30_00.38.49-server.txt

Thanks for reporting. I'll check it out

Should be fixed now