Hi Steve,
It looks like it is a decoder issue actually.? I've been working with a new loco and decoder (DCX76) and am still fiddling, but maybe the SPROG is overloading or something.? ?Can't see anything wrong with the wiring, but have run a couple of other locos ok.? But if I restart JMRI it talks to the SPROG again until I try to programme something than the comms LED stops flashing and I can no longer get the Status to change.
But my JMRI version is 4.18+R36ad3do
Ralph