Rasa train API return 200 but rest response null

I delete the my model with the unload the trained model API and then try train API. This is result:

I don’t understand the response but status is 200 so i think it is successful.
The i post a message to rest API but the response is null Does anyone know about this issue?

My rasa version is 2.0.0a2

I don’t know the reason but it’s work today. I think it’s need some time to run with new model.