This has happened twice to me and always coming out of Iranian airspace.The only thing common to both incidents was that we were running late and we had to adjust the eobt to stop the flightplan disappearing.The last time it happened the UAE controller( an aussie??)said that the ruling was from above!I told him that we did that route three times a week with the same two aircraft and the plane had been RVSM since it left the factory ,but he was powerless to make a dispensation.I always get the company to refile the plan now if we are even slightly late.