Thanks for the quick reply.
So the stock themes shouldn't actually be in the user-defined folder? Or is the issue that the user-defined folder path should not be pointing at .../data/maps/earth?
I didn't manually put the stock themes there, this is simply how it was in 2.6 and I guess it stayed that way.
So I should simply delete the stock themes from the .../data/maps/earth folder, since they're now stored somewhere else? And only leave my custom themes (Google) there?
Or change the user-define path to another directory?