Thank you for the project. I have been able to reproduce the issue.
The missing link was the Reload Domain as that was allowing the activeEmitters list to hand around after relaunching PIE. A work around is removing the if (!isQuitting) check from the OnDestory() function in the StudioEventEmitters.cs. This will result in all Studio emitters stopping when their object is destroyed however. A task to address this issue has been made and will be included in an upcoming release.
Thank you for brining this to our attention.