It appears that if you create a Matinee in a Sublevel, and then subsequently move the matinee between levels. It will not keep associations with the attached actors in the Matinee and not trigger events.
Behavior does not appear to be a regression from 4.8.3, however the Warning about confirming you want to delete something does not appear in 4.9.2
*Quick Reproduction with attached Project*
*NOTE: You can move the Matinee actor back to SubLevel_01 and the connection is still broken, i.e. it will yield the same results listed below*
RESULTS: Particle System is never triggered from Matinee
EXPECTED: Particle System is triggered from Matinee
*FULL REPRODUCTION, including project setup*
*NOTE: You can move the Matinee actor back to SubLevel_01 and the connection is still broken, i.e. it will yield the same results listed below*
RESULTS: Particle System is never triggered from Matinee
EXPECTED: Particle System is triggered from Matinee
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-22313 in the post.