In creative mode, if the player is near the Trials spawner, it will not be able to summon mobs
This is almost certainly intentional due to what was written in the 23w45a changelog (the snapshot which added Trial Spawners):
Creative and Spectator players cannot be detected or noticed by Trial Spawners
Reporter: fuerfei
Assignee: (Unassigned)
Created: 2024-06-30T02:11:43Z
Updated: 2025-04-29T15:29:21Z
Resolved: 2024-06-30T05:59:24Z
ADO:
Confirmation Status: Unconfirmed
Area:
Mojang Priority:
Category: Mob spawning
Labels:
Affects Versions: 1.21
Fix Versions:
Retrieved 2025-06-11T04:22:53Z
This is almost certainly intentional due to what was written in the 23w45a changelog (the snapshot which added Trial Spawners):