Trial spawners that have had spawn eggs used on them revert to their initial state after their cooldown expires

Just updating this as I've figure out the exact issue

• Get a Trial Spawner or save a structure with a Trial Spawner in it
• Place the Trial Spawner or load it from a Structure Block
• Use a Spawn Egg on it
• Defeat all mobs in the Trial Spawner
• Wait 30 minutes for the reset (The pinned comment says you have to go into creative during this time)
• You will notice that it either has no mob or has the original mob spawning instead of what you put into it

While I haven't tested it on ones in a trial chamber this likely is an issue on them as well.