FWIW, I was out on Mil Leave for 60 days and lost access to the online reservation system as well. I was told that I could jumpseat online but that I had to call jumpseats and that they'd make a special mil leave profile. I never did this, but my jumpseat reservation access didn't come back until I called jumpseats and informed them that I was back from leave.
I didn't try to jump offline either.