GPO Import Settings error

[Sheridan]

I'm trying to import some GPOs from a Server 2008 backup to a new Server 2016 - most are working when I create a new GPO and then Import Settings from the backup of the old GPOs.However on a couple (naturally the largest and most important GPOs!) I get the error 'The library, drive or media pool is empty' when trying to import. If I try to view the settings before I get the error 'A unknown error occurred while the HTML report was being created'Neither of those errors tells me anything, and quick search on the first error only seems to bring up file copy related errors - anyone got any idea what on earth these mean?