I recently upgraded to 6.9.2 just before initiating the below so not sure if issue would have been present on previous versions   After upgrading to 6.9.2 i cleared my cache and array and started to use BTRFS encryption for cache pool and XFS encryption for the array, in addition i started using Secure instead of public shares.   Prior to this i had no issues and all files would be owned by 'nobody'.   I have noticed on 3 seperate occassions now an issue where my SM