I dont see anything wrong with either the description.ext or mission.sqm
ofcourse you already knew that.
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Suggestions
Try a simple debug mission, same respawn, just a group of FDF 1.4 units on the same side, nothing else on the map and kill one of those units, see what it respawns as.
Try it on a client/server and on a dedi server in real mp
If it respawns as a standard BIS unit, something majorly is wrong
and i would suspect a config error somewhere in the mod. Perhaps the class of unit has a protected scope and is reverting back to a mother class. This really is an oddball
if it respawns as the same class unit then the mission has to be at fault, but what could cause such an issue, maybe a grouped gamelogic or something like that perhaps
I've never heard of this issue before and thats in what 5 years of OFP now
Good luck, please post your findings when you fix this problem, i would be interested to know