[Issue] Invisible silverfish on friendly mobs - unable to attack friendly mobs

[ksduster]

Describe the bug

When a friendly mob spawns, an invisible silverfish spawns and attacks all players. It does not disappear, cannot see it, and cannot protect yourself from it.
The friendly spawn is not able to be attacked.

How to reproduce

Spawn a mob using the command or let it spawn automatically.
Be attacked by invisible mob. If killed by it, it says it is a silverfish.

Screenshots / Videos

https://youtu.be/GGe9GJX76JI

Server Log

https://mcpaste.io/0d7c188f08394e0b

[Luca-Biraghi]

I have the same bug.
My logs have these lines in common with yours

[20:23:03] [Server thread/INFO]: [AdvancedMobs] Enabling AdvancedMobs v1.18.12
[20:23:03] [Server thread/WARN]: You are using invalid version of Minecraft [1.21.11-R0.1-SNAPSHOT]! Disabling...

maybe the AdvancedMobs plugin does not recognize the 1.21.11-R0.1-SNAPSHOT Minecraft image as compatible ad loads just partially.

Let's wait developers give us some hints.

[Elbal00]

I have the same error.