Was checking other stuff on Tundra, and found this couple of times which they spawn in a location that suffocate them helplessly:

https://ibb.co/k0qsQs9
https://ibb.co/cCdhsFQ
https://ibb.co/qy13HKx
https://ibb.co/rtQjx8f

Maybe let them break certain blocks? I'm using the latest version of the mod and 1.16 minecraft. Love the mod!:)

Faced same "stuck spawn" too on 1.15.2 (this modpack)