Roo Stercogburn
Sonar & Melodyne interactions are bug-ridden.
Cant say I agree with this statement at all. Ive used Melodyne as a Region effect for 2-3 years now and have yet to see 1 single bug. I should add, I don't ask Melodyne to fix full tracks, or every track. I use it to fix sections that are either A- out of time, or B- out of pitch. I also bounce the Region FX after every edit.
I know there are some users who have had problems using Melodyne, saying it crashes their system but I have yet to see any of that. And the users who have complained, ive yet to hear one complaint of a silent track, silent audio like the OP.
Back to the OP:
Make certain you don't have any Mute or Solo buttons engaged on any tracks.
That's about all I can think of.