I'm not quite sure how it works anymore, cause i haven't used that feature since the MSFS Alpha, but don't you need a flightplan on the worldmap for that to work? As the flightplan in the FMC of the A310 is totally uncoupled from the flightplan on the worldmap, I don't think you can use - or at least there is no guarantee it'll work - that feature with the A310.
@FelixMThe issues with pausing the sim are known and are being worked on for the next update π