Please check "handler advance" option is selected in the step

The handler advance option when true (checked), will advance the workflow to the next step after the current process is done with its execution.
In case the handler advance option is false (unchecked), the process script has to take care of advancing the workflow to the next step. In case the script doesn't handle this, the workflow would remain in the running state without proceeding further from the current step.
Regards
Albin I
www.albinsblog.com