i have the same problem

Normally after selecting save and exit, I can resume next time I play. But sometimes I cannot. This doesn't just happen after Arma 3 updates. It once happened after I died, and once happened after the game did not close cleanly (due to a segmentation fault or something similar). I love this scenario, but this has happened the last two times I have played, and greatly reduces the enjoyment I get from this scenario I don't know if the issue is with the scenario or is with Arma 3, but I hope that this issue is addressed soon!