Hi,
I have the same problem this week,downloaded mp3 files from the same source that I have been using for years no problem!
Out of the 40 tracks only 16 would show on genos,tried different usb sticks,still the same.Been in touch with yamaha support and the source,very helpful in explaining the tech issues with Genos and MP3 files, as regarding the titles some of the long ones load ok,but the short characters do not. All the files show on the usb and play on my PC? tried all the ports too! will try to send the file that wont load on my Genos to support and see if they have a problem on another Genos to eliminate the problem!