This still doesn't justify the fact that with the SA-5 you either hit the target at very close ranges (so far the highest detonation range that I experienced was 18 meters) OR you completly miss the target - there's NO "middle term" like a 50 or 100 meter (or even longer) detonation like happens with the other SAM systems (SA-2 and SA-3 for example) and this happens either when firing against a SR-71 or against target drones in the firing range (and both with or without jamming).
I would expect that at least when shooting drones in the firing range that some longer distance detonations (again with values like 50 to 100 meters or even more) would be experienced but I haven't experienced NONE and believe me I've been shooting a lot with the SA-5 latelly (specially in the firing range).

I checked the code, and the Vega part still has the 300m sensitivity. (bit too much)
Did you receive KRO signals during missile flight?
If the set range is far from the real target range, the missile engine program might cause the missile to burn.
Also, as the missile decelerate during unpowered glide, the chance to hit anything is reduced.

I think your missiles that not scored, avoided the target by far margin.