testing using real devices only
It might be a good idea to look at the logging for this behavior when you stop the engine before the view controller is dismissed to see if it is able to shut down cleanly.
Please verify that this isn’t a Simulator-only issue with stopping listening. Generally, no Simulator-only bugs are taken as reports here, from the post Please read before you post – how to troubleshoot and provide logging info here:
The Simulator can’t be used for testing or evaluation with OpenEars (there is more about this in the documentation and the source) so please do not submit any questions or bug reports relating to Simulator results.
If this can either be replicated on a real device or disproven that it relates to Simulator environment differences from the device, I can help further.