If you go Visual Perspective > then the Details button you get a window and in the panel/box titled 'Platform Support' you have radio buttons with options...
If you select 'Desktop and Tablets', the system fails to recognise this for 8 inch tablets (and throws an error saying no visual perspective is defined). We haven't tested (because we don't have the hardware) but we assume it would do the same fail for smaller 7 inch tablets too.
The workaround is to have 2 Visual Perspectives, that are identical, one has 'Platform Support' for 'Desktop and Tablets' and the other has it for 'Phones and Tablets' . This isn't ideal as you have to now maintain two (or more) VPs.