Baffling MIDI track will record and scrub but won't play

On a strictly MIDI project I transferred from CWPA9, everything was playing sweetly and tweaking nicely. I saved it as a "normal" project file in SONAR (PE8.5.2). When re-opened the next day, all MIDI tracks were playing except one--MIDI ch 2 driving part 2 on a JV-1010. I had not made any changes to this track. I checked all my outputs, assigns, solo/mutes and levels, checked event lists for spurious PG, VOL or other CC commands, none. In PRV, the track events scrub ok--the JV-1010 receives MIDI and I can hear the events. But hitting play gives no MIDI output on that track and thus no sound from the JV-1010 on ch 2 though all other parts are fine.
 
I re-load the ProAudio9 .bun file. The conversion to Sonar occurs, and the problem track plays as it did the day before--before any editing and saving as a Sonar project file. Just to check, I verify MIDI playback on the problem track, make no changes and save again as a SONAR "normal" file with a different name. Reboot, reload the new file, same problem. I try cloning the track, assigning to another output, importing different midi events to it, all without success.
 
Finally, I copied the clips to a new track, set it up with the same preset,  channel, and output. Couldn’t find one iota of difference between the two tracks, yet the old one wouldn’t play and the new one would!
 
Later, the same problem occurred on the same project, but a different track, different MIDI channel. No edits or tweaks had been made to that channel–it just stopped playing in real time, though it would scrub. Fixed by the same aggravating work-around. It’s as if Sonar PE can’t handle more tracks than there are MIDI channels.  I'm anticipating another repeat of this phenomenon.  Has anyone else experienced this?
 
Windows XP sp3/Intel DX48BT2 v. 1893/Intel Core2Duo 3.0 GHz E8400
OCZ 4 Gb RAM (2x 2048MB DDR3 PC10666 1333MHz)
Seagate Barracuda 750 GB SATA 7200.11
Digital Music MX-8
LynxONE
Roland JV-1010
Emu Planet Earth
Yamaha DX7
Roland U20
 
 

Sorry, I did mean .WRK instead of .BUN.  I've been making the transition from PA9 to SPE 8.5.2 for a few weeks before upping to 8.5.3.  I don't see what the stability and AudioSnap improvements have to do with my problem, but will install anyway and try again.

Yes, all MIDI was routed to the LynxONE outs to the MX-8 MIDI patchbay.  I haven't gotten to soft synths yet.  I wanted to fix this problem first to resume the workflow I had with PA9.

I upped to 8.5.3.  The problem persists.

I'm answering my own question, after working on other things.

This phenomenon was not unique to one project or to any one instrument or MIDI channel.  I went round and round with tech support via email who totally misunderstood the problem and were of no help.  I haven't figured out why it happened or how to prevent it, but here is a workaround, if anyone else has the problem:

Simply cloning the track will not work.  The glitch that prevents playback is also cloned.  Instead, I inserted a new MIDI track with the same instrument definition, then dragged the events from the non-playing track.  Voila.