Hi, I'm using InControl to spawn in some of your mobs into the overworld where the larger ones (greater than 1x1 footprint) are suffocating since they'll spawn next to a 1 block incline or more. Since I haven't seen this occur in the Misty dimension, but I also haven't had any issue using InControl with large mobs from other mods, I suspect you may have a custom handler for collision detection on spawn? Regardless, I figured I'd let you know in case its helpful. Thanks for the great mod, wonderful models and textures as well as really creative mechanics!

Version info:
Minecraft: 1.12.2
Forge: 14.23.5.2847
MistyWorld: 1.2.5.1

Not sure if you still need it, but.
https://wiki.mcjty.eu/mods/index.php?title=InControl
Here is a wiki on InControl, there is a special check isnotcolliding: so they don't suffocate. Maybe you should run it.

I’ll give that a try, although I’m pretty sure I’ve already tested isnotcolliding and it had no effect.

May i see your "Spawn.json" script. Maybe i would be able to spot the issue. If there any, of course.