RB can't see all my music. Rockbox newbie here.

[MurrayF]

Hi all.  I hope some of you can help me.  I have just got rb running on a gen 6/7 ipod classic.  However it only shows about 100 music files on Now Playing.  I put all my music files on the ipod via cable and they can all be found under I\music\mp3final\<artist> directories when connected to the computer.  There are about 99,000 music files there, mostly mp3 but some m4a , flac and wav.   However, on turn on, it only shows one of the albums from the apple section of the ipod (ipod control).  My computer is a win 10.
Someone on facebook said to go via files and/or database, however, it can't see all the 99k songs.  Is 99k too much for a gen 6/7.
The ipod has succesfully got 2TB, using a iquad board with four 500MB sd cards.
If anyone has a magic wand I can wave over it to get it to see all the music, I will be forever grateful.
Also, is there a better theme to use?  I'm not sure if the one I am using could be an issue, or not. See attachment.
Thanks in advance.