its not an access issue, sonarr is importing it with no issues, something is deleting it afterwards and when sonarr does its next series/folder scan it sees them missing and flags them as such (youve probably got ignore deletions enabled so sonarr is telling you theyve been deleted and its not going to download them again)
you need to work out why they are getting deleted. if the storage path is underneath the download path its possible its getting deleted when you purge the job from the download client. they really need to be completely different paths to ensure that cant happen