Where are you moving the content to? It may be checking permissions against the parent folder. If you're trying to use C:\content, for example, then it may be trying to check if it can create the content folder on the C:\ drive. If the content folder already exists, perhaps that has to be accounted for in this check, like check the parent folder if the content folder doesn't already exist.
OK so we got it sorted.
The bit we missed was adding the isConnectionStringEncrypted":false
All went through ok after that JQuinn-esristaff