So I've got this 80s synth with a wacky 16 track sequencer that's really an 8 track sequencer with the remaining 8 tracks only available in Song Mode.
 
16 tracks gives you 16 MIDI channels, but when playing a 16 track project in Sonar using this synth, it will assign all 16 tracks their correct instruments but only 8 tracks will play, either sequence or song, but not both.
 
To make matters worse, the manual was written for the older 8 track version so it is unclear if this is truly a limitation of the synth.
 
To overcome this limitation I bought the rack module version of the same synth and route the remaining 8 tracks there.

I'm not sure if there's a question here.

Might help if you told us the make and model of the instrument. 

I was only conveying a workaround for a perceived MIDI limitation in case others had similar issues.
 
BTW, the rack synth has the same limitation.
 
Ensoniq SQ1+/KS32 series. Original SQ1 was 16 voice with 8 track sequencer. The SQ1+ had 32 voice and 16 track sequencer.
 
Steve