Tom, can you specify what "some of these suggestions" mean?
Try this:
- Make sure Apple Music subscription is disabled on the iPad
- Check in the iPad music app that you see all your songs and can play them back
- In the iPad settings, scroll down to Stage Traxx and check that access to the music library is enabled
If you needed to change any of the above points, stop Stage Traxx in the task switcher and restart it to see if the songs now show up. If not, do this:
- Open Stage Traxx
- Open the Playlist Manager (top left button)
- Select a playlist with missing songs for editing by tapping on the (i) button
- Missing songs are red, select one red song
- Tap on the "Repair iTunes link" button on the bottom of the window
- Browse to the correct song in the iTunes library and select it
Repeat above steps for all missing songs.
If this still does not help, tell me exactly what you tried.