Hello!
For now lightning emitters are not auto-activatable and you need to execute “Spawn lightning” function from blueprint code to activate emitter.
The “Run emitter” (as well as “Spawn lightning” function) button executes emitter just once, not in a loop. Did you see a lightning curve itself? If so - it is not a problem.
But if not - then try to activate emitters on Example map (in runtime), maybe there some issue in parameters of your emitter.
If your problem is still not resolved, please tell me:)
I will definetely add emitters’ looped execution and auto-activation in the next update.