ok, if its the white usb stick, then its known to be pretty unreliable after a while.
so I’d ditch it, and get a new branded one, something like a sandisk.
you should just delete the favourites.txt, then try to add a favourite.
just to be clear on how you are ‘storing favourites’, you need to load the patch
then you can click on ‘add to favourites’ , and it should appear.
(and you can verify by checking the favourites.txt file later)
… really there is not much to it, its just writing that file, and then reading it to display to the user, and allows them to select - if its not working, (and the fact your ‘save’ does not work) really seems to point to the usbdrive.
(only other thing I can think of is if your using some weird names, with odd characters, for folders or patches, but I suspect you would have guess that already )
factory reset should not be needed, but if you want to, then its just writing the image to the sdcard.
if your going to do this, grab a new bigger sdcard, so you can start storing patches on the sdcard
various posts about this on the forum
frankly a bigger sdcard (so you can store patches) and a cheap wifi stick (see recommendations) are the best investment ever on an organelle - Im amazed there are people still bothering with a usb stick … I found it so tedious (and error prone) - the wifi/sdcard workflow is so much better imho.