Bossbars and actionbar messages from mythicmobs are not showing

This is a copy and paste of an issue I posted on Mohist. But I actually don't know if it's an issue from MythicMobs or Mohist. But the issue is appearing with versions above MythicMobs-5.6.2. (5.6.2 works fine) and on Mohist (Paper is fine) https://github.com/Teneted/Tenet/issues/3687

Minecraft Version : 1.20.1

Mohist Version : 8b58922

Operating System : Windows 11

Concerned mod / plugin : MythicMobs-5.7.2 or above

Steps to Reproduce :

1. Setup a mohist-1.20.1-8b58922.jar server with no particular parameters
2. Add MythicMobs-5.7.2
3. Add a new basic mob with a bossbar like explained in the official documentation

SuperCreeper:
  Type: creeper
  Display: '&cTest'
  Health: 20
  BossBar:
    Enabled: true
    Title: 'Test'
    Range: 20
    Color: RED
    Style: SOLID

4. Perform /mm mobs egg get SuperCreeper
5. Spawn the mob and realise that no bossbar is being displayed

Description of issue : So it's a pretty basic setup and if you do the exact same with paper 1.20.1 it works without any issue. But with Mohist, the bossbar just doesn't show up. There is also the same issue with the actionmessage skill, maybe it is related.