Hey all
Am only posting this in case it helps others / or if others have also had this happen.
- KPA with 3.0.2.951
- BJ Devices TB-12 Midi Controller - Bi-directional MIDI with Browse Name and Tuner Display
- Atomic CLR Active Wedge
- Dunlop VolumeX Midi Pedal
Last 3 months - all good - no issues.
Out of the blue, this is what happened tonight
- I was changing banks and programs [ only in Browse ] mode with the KPA
- after about 2 hours the TB-12 pedal and the KPA seems to " loose" communication
- I pressed the buttons on the TB-12 but the KPA didn't respond
- I powered off / on the TB-12 - no change
- the KPA and TB-12 weren't "talking to each other" any more
- I went to the KPA and tired to manually change to a different Browse rig - nothing
- I was getting "desperate" so I pressed the " Amplifier " [ Stack ] button to see if maybe it responded and the unit just immediately shut down but not powered-off-fully 
- I switched it off and it "hung" on shutdown for a long while [ 30 seconds or so ] and then eventually it shut down but without the usual shutdown-screen-progress bar
- I powered it up -and it booted very slowly- and then finally went back to where it was, but everything was still locked up
- our other guitarist - who also uses a KPA thanks to hearing mine 
- came over and said [ to my surprise ] that he had a similar issue the other day and what he did was to
( a ) unplug the Midi IN / OUT from the back of the KPA [ he has an RJM pedal ]
( b) shut down the KPA
( c ) power off his RJM pedal
( d ) plug all the Midi cables back in
( e) Turn the KPA back on
( f ) Power up the RJM
( g ) All was fixed and back to normal
I did the steps above and .... whew ..... all was fixed
I'm actually not stressed or worried about this .... my sense is that there was a glitch ( midi overflow ? ) between the KPA and the TB-12 .... especially given that the above steps fixed it and the units were in a bi-directional connection.
From my experience in the past, midi can be quite temperamental sometimes
Finished off the night no worries.
Like I said, I'm not concerned about this, as should it happen again, its a very easy "fix" - basically a cable unplug / re-plug and a re-boot ..... but I did want to post what happened and what we did to fix it in case others have or may see the same issue.
Ben