• This issue is not solved in a development build

https://mclo.gs/pw9GRO3

Version 591

This is a MyPet issue, basically receive listeners are now called sync as well if not specified differently. They are deadlocking the server thread by waiting for another sync operation to complete.

use Version 587 can work with MyPet

Instead of downgrading I would recommend contacting MyPet so that they fix the underlying issue 🤔