Answer is not shown in message thread after posting a new reply

In 3.0.1 writing ansers in existing message thread does not work anymore.
The answer is posted, when the "Send" button is pressed, but the answer does not appear in the message thread. The user has to reload the page manually to see the new own answer. Autloading message thread after subitting the new answer is not working anymore.

This works fine in v3.0.0.