I can replicate this issue on the BETA build of DAZStudio. Tracing through the DAZStudio shutdown process shows that the Octane plugin is being successfully closed. I think DAZ would need to trace through their code to see what the issue is.Not sure where else to report this, but since upgrading to the latest version of Daz Studio ( 4.12.1.117 ), Daz will not shut down after closing the its UI - it can be seen in Task Manager with the same memory allocation and no Processor cycles, sitting indefinitely until force-closed.
Paul