i am the creator of the mission "invade altis" and i had several user complaints about non-solvable side missions.
i use existing editor objects (e.g. trafo stations) in my side missions, if the player destroys them, the mission is solved.
since the last mission, the "damage" script call returned the correct damage of the objects, since 1.14, the reported damage is always 0 - i checked the return value today with "diag_log" after the user reports.
the users also reported, that they had the same issues with other missions and i too did not change anything regarding that issue, so IMHO it is a 100% ARMA 1.14 issue.