Pitch Wheel event at beginning of an SMF causes import to lose tracks
Please see this forum discussion thread for details.......
In a nutshell the occurence of a pitch wheel at the beginning of an SMF track causes MuseScore to ignore all tracks except those assigned for percussion.
In this case the Pitch Wheel events were at the beginning of a percussion track assigned to Channel 10 as is normal GM practice. I haven't established whether this is significant or not.
The SMF is attached.