Hiya
Transfer the files IN the folders 'chunk-by-chunk'
eg, all the A's, then B's .. or 4 pages at a time. I had this issue.
Hardest bit is remembering when you go back, where you got to!
Unlike Windows, you cant open more than one folder!
*Remember on the keyboard, when you select styles to browse, you wont see other file types, and cant copy those, until you select those types of files from the panel (like Pad, Registrations, Voices, etc)
You'll get the hang of it.
Unfortunately, Yamaha do not use a file Explorer, like we know from PC's!
Al.