I am thinking JMRI did not dump the address properly. Try selecting your engine, make sure it is in forward, with no functions active, not in a consist, and then dispatch its address from your throttle. That should force it out of the system. This is the only for sure way I have found to dispatch an address from a throttle and actually dispatch the address. Digitrax is very persnickety sometimes.
Sometimes, at least for me, when JMRI doesn't work, hard resetting the system (with the OpSw for Digitrax) is the only way to for sure dump the system.
I have seen this problem happen before as well, can't select your address no matter what, but reprogramming the address works. Usually when this happens I have hard reset the system and it works. It sucks, but sometimes that is necessary.