Summary
Since like half a year or ever there is a "bug" where Mythic Mobs cant create items correctly. This is a Major issue if you are using different Plugins like villager market, custom crafting etc. where you want the player to trade in Mythic Mob items with the exact Item Meta. After reloading custom crafting or Villagermarket while they have Mythic mob item will cause the item Meta to be rearranged. You need to Convert the Legacy meta from Mythic Mobs, to be able to use it at all, which can be very resource intensive for you Server and is unnecessary.
Hope you can follow along!
Steps to reproduce
Here is my Video https://youtu.be/6Ch5uW2Ixes
Current behavior
Using MM items in CustomCrafting or VillagerMarket etc is basically useless. After Reloading CustomCrafting etc Items can no longer be used since MM uses Legacy Item Data.
Intended correct behavior
What should happen is to correctly format Item Data to be used with other Plugins.
Server log file
Here is my whole log from today https://pastebin.com/uCVFtLKL
Debug log snippet
Proposed fixes
Fixes might be to use Modern Item conversion instead of Legacy.