if ANYTHING steps on a magma block it crashes our server, and if mob is still on block when server on it insta crashes again

Put the summary of the bug you're having here
somehow when ether a palyer or a mob steps on a magma block on me and my friends Personal server it instantly crashes it, currently i can not join becuase when i do a skeleton around my area is stepping on a magma block instantly crashing our server

Steps to Reproduce:
1. place magma block on server
2. ...step on magma block or have mob on it
3. ...crashes server
that detailed enough?