When using the Spawn Emitter at Location node in BP the emitter will not spawn while simulating in BP. Other Spawn at location nodes behave the same way. The Cube actor was included as a test to eliminate some suspicions.
Cube actor was included in test to disprove suspicions mentioned in comments.
Cube spawns in BP editor
Particle Emitter and Cube Spawns in BP editor
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-35717 in the post.