child 'animate' not valid here

Version is 1.16.0.59 but I could not select it from affected version, and I report the bug anyway because I didn't find anything related in the last changelog so I assume it can happen too on latest beta.

I am trying to trigger entity events on server side, on the behaviour pack as stated in the doc:

Entity events doc

On level startup, there is an error appearing at the top of the screen: child 'animate' not valid here, although it is just as stated in the docs, inside description -> scripts property on mob.entity.json

. And the entity doesn't emit events either.

See attached .gif for full error.