I originally tried to play 1.21 on my BDS with addons, but after loot wasn't generating and after some testing, I found that older worlds in general don't produce trial spawner loot. Not sure what causes this issue but it's insane that it made it to release.

Expected behavior:

-Fly out to a trial chamber in new chunks

-Kill mobs spawned by a trial spawner

-Obtain loot from said spawner

Actual behavior:

-Fly out to a trial chamber in new chunks

-Kill mobs spawned by a trial spawner

-Trial spawner plays opening animation, but no loot generates