Unknown Running Error while testing

Hi there, I come up an error with the message "failed to create a child event loop " when I am trying to run the test benches, or sometimes no error message sent while the software is not responding after I click the 'run' button. 

It occurs after I have opened and closed a certain number of test cases and I have to kill all running Pycharm related tasks and restart it to fix that which is really annoying.

Do you know how to fix that?

Thanks.