My USB music is playing fine now I've sussed it out. I use a USB C stick.
I'm on Info software R40.
At first it did'nt work ... it took a while scanning and reading all the tracks when plugging the stick in but then did'nt display any of the songs / folders / albums at all, and just played any song at random which I could'nt control !!
From experience with a VW Golf I tried reducing the number of album folders right down, to limit the number of tracks and album folders. It then worked OK and displayed the album folders and pressing on the folder opened it up to show all the tracks. I just then touch the first track and it will play the whole album/folder in order.
Where it displays "Play All" (top left), if I press on that it switches to album folders. I then worked out how to play each folder in sequence, rather than random (look at the symbols under the blue track length line) . My screen looks like this now for playing album folders with each track in sequence.
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