i just run into this... single player, free flight, just me on the map.
i don't know if this has anything to do with the problem, but i
paused 2 or 3 times while watching the track.
some time around 10 minutes after the start, it started loosing
altitude and crashed over a group of trees (while in reality,
i headed back to the airfield and crashed near a lighthouse).
then, i replayed it one more time, now with 2x time acceleration.
it almost got to the same point as before, but then it crashed
over another area.
maybe it's not loosing sync (only) while recording, but while
replaying. i mean, it's not always the same replay after that
point.
:(