Entities summoned using a non-default event will not run their animations until reloaded

Partner Rank:

1

Partner Team Reporting:

Everbloom Games

Verification builds:

1.16.100.56

Summary:

Entities summoned using a non-default event will not run their animations until reloaded.

Impact:

Server animations are a cornerstone of modern map making, and summoning with custom events is also a pretty useful thing. Anything that combines these two is unfortunately broken.

Off the top of my head, affects Ninja Mash-up and Ninja Parkour (grappling hook, and all the moves leave lingering entities that can build up extremely fast and lag the game, not to mention push the player around wherever they've been)

Repro Steps:

1. Open the provided world
2. Go to the area with 4 buttons
3. Head to the white-floored chunk with 4 buttons
4. Press the three buttons labeled with "summon"

Expected:

Each time you press a button, an entity should be spawned. An animation attached to it should say "animation started", and kill the entity after 0.5s

Observed:

The behavior above only occurs with the first and third button. The second button, which spawns the entity using a custom (empty) entity event, spawns an entity which does not run its animation (and thus, it neither says something in chat, nor does it die after 0.5s)

Screenshots/Videos attached: Yes/No

Yes

Regression Builds:

This last worked in 1.16.100.55

Notes:
EDIT: This also breaks default spawn events if the minecraft:entity_spawned event is overwritten by the entity definition.