Can't continue the campaign with certain savegames

Hi all.

I was about to finish the fifth Arma II campaign mission, "Razor Two", when by some mistake I reverted to the beginning of the mission and all my saved games seemed gone (didn't appear ingame). This bothered me a great deal, because I was playing through it for the third time and finally managed to get all the evidence and get to Bardak in time. I thought I was in luck when I found the saved games in my "home\Documents\ArmA 2\Saved\ca\missions\campaign\missions\C2B_RazorTwo.Chernarus" folder. I opened the last one with the OA executable and reloaded the game successfully. However, although I can finish the mission, it will no longer advance the campaign. Successfully ending the mission does not unlock the following one. Also, after loading the savegame the "Suspend" option in the menu is replaced with "Abort", and it will delete all mission saves, or so the message says. Saving in a new slot and reloading that game doesn't change this. I've tried copying the old save somewhere else, like "home\Documents\ArmA 2\Saved\ca\missions\campaign" but it didn't work either. Only restarting seems to restore the normal menu behavior (and would likely allow me to continue the campaign).

Looks like this behavior was intended (perhaps as an anti-cheat measure?) but as I mentioned I have already played through the mission three times and wasted a lot of what little free time I have, and I'd rather make that old save work if it's somehow possible. Does anyone know of a way? Thank you.