Do you have any plugins on the channel that doesn’t sound? For instance a gate set so it never opens? Try disabling any plugins and see if you get a sound.
Are you sure of the Output routing setting in the track inspector ?
Have you checked both the state of the Monitor button in the track header and The Edit > Preferences > VST > Auto monitoring setting ? There are combinations of them that can lead to a muted playback.
How is the Gain set in the MixConsole for this track as, yes, its setting can more or less mute the playback of it in certain circumstances. The better is to set to 0, when playing back a given track.