My initial report of zero psi was due to a stuck valve. But it was very low as discovered by removing the valve.thanks for updating the thread. it is nice that it was a simple solution too bad you already had the axle out by the time you figured it out. must by industrial tires the carcass is so stiff it doesn't go flat even at 0 PSI.
I think an important lesson from this is to check tire pressures even if they look fine.
I feel very blessed to have been given the solution before tearing into it further. It took less than a half hour to get the axle back on.