We were unable to reproduce the issue you are describing. It is likely that there may be something else going on with your environment and setup.
We tested with the following workflow:
1) Run a simple 'ping' cmdrange job
2) Block the job while it has a running subjob
3) Unblock the job
Result: Job completed fine.
Send us an email at support@pipelinefx.com and we can dig a bit deeper into what is happening for you.
Regards,
Scot