The way that Yamaha implements 'Favorites' is a joke!
Although you are limited to just 100 files, even if you could include non presets, who in their right mind would program the OS to list them in the order that they were added to the list rather than alphabetical order?
Only Yamaha with their impeccable logic!
How stupid is that?
Instead, if you want to group files into favorites, forget Yamaha's stupidity and make your own folders for them on the USER drive or a USB.
Then copy your favorites to these folders. You will be able to add presets, USER files and ones from USBs/HDDs to these folders, and although it will use additional memory space, since it will make a copy of each file in the new folder rather than just a 'link' to them (which presumably is how 'Favorites' work), on recent keyboards this should not be a problem for the USER drive, or just use a USB drive instead.
The files will then be listed in alphabetical order, giving you a chance of finding them easily!
To date Yamaha haven't managed to mess up the file listings on USER and external drives - but give them time!
If this sort of stupidity was was implemented by a 'lesser' manufacturer such as Casio or Medeli, they would be slated on this forum!
Regards
Ian