I've got a number that I did I think in Sonar X1c originally.   Currently have Producer Expanded X1d, just re-opened the project to do some fine-tuning.  I have some tracks that are panned pretty hard (eg 75%, 86%), but everything is playing centered.  I can't for the life of me figure out why.  Read parameters are enabled.  I'm not finding anything in the path that should cause it to ignore the panning -- no clip panning, etc.  I've shut everything down and back on.  I've moved the panning to 100% and it's still playing back centered.
 
Any suggestions on what's causing it, something obvious I'm overlooking?

Without knowing your system specs I would be guessing, but do you have a mono sum switch enabled somewhere,
perhaps on your mixer, if you have a mixer. What about, did you freeze these tracks while in their panned position ?

Are these Mono tracks or Stereo tracks?

If they're mono (only 1 waveform visible) then they should pan as expected.

If stereo, you need to look at the track interleave

I don't have an external mixer, all done on Sonar software.  These tracks are not frozen.  (For my learning, what does freezing them in the panned position do -- wouldn't that keep them panned anyway?)

They are mono tracks.  I tried with and without track interleave on just to double check, made no difference.

Obvious checks...
Is there an FX in the Master that is mono?  or set to mono?
Is the stereo button on the Master set to stereo?
Does the output meter on the Master show a stereo signal? (The two meters move differently to each other)
If you pan an individual track does the track meter show a stereo signal?

Checked all Fx, none are set to mono.  Turned off all Fx in whole project, no impact.
Master DOES show a stereo signal.  If I pan Master, it pans appropriately.  But for tracks and busses does not pan.  (Signal path is vocal --> Lead bus --> Master.)  Track panning and bus panning has no impact; master panning works appropriately.  When I pan a track or bus, the signal meters still show a uniform stereo signal, no change from left to right.

I opened several other projects, and everything pans appropriately, so it something specific to this project...

More stupidity checks...

Mono FX in a bus?
Bus set to mono?

What if you  send the vocal directly to the Master?  or directly to the soundcard output?

I checked all Fx in whole path, couldn't find any mono settings.  Turned each Fx off in Fx bin.  Also turned all Fx off for project in control bar.  No change.

Same for each track in project, not just one track.

Rerouted track to go directly to Master (bypassing bus).  Still pans at Master but NOT at track level.  Rerouted track to go directly to interface oputput, bypassing bus and master, this DOES allow the track to pan.

Can you post a screen shot of a track you're trying to pan

What about your interface mixer?  Mine is always playing tricks on me if I don't doublecheck.