Hello,
when processing star metal on the server, the player kicks with the reason:
"Rimil lost connection: Attempting to attack an invalid entity".

I checked in a single game, everything works fine, it doesn't kick.

Also tested on two cores: Mohist and CatServer.
The outcome is the same, kick from the server.

As an example, I attach a screenshot from the Mohist core:

I also want to note that everything works stably on the mod version 1.13.12.

I apologize if there are errors here, I used a translator. <3

Bukkit/Spigot/etc are not supported by this mod, which both those server hosting types include as part of their deployment.