Nope, you're not missing anything. I've brought it up before. In fact, it's a holdover from CMANO.
In the last CMANO update BEFORE CMO came out, I started seeing SEAD units firing off HARMs at real long distances. Like yours, they ran out of fuel and fell to the ground.
From what I have been able to figure out is that when an aircraft goes on the OFFENSIVE, there has been new approaches as to how that is now handled. I say that because CMANO never used to do this.
As you have seen, even if you have the Doctrine set to PESSIMISTIC, it will still fire as soon as the target in area of uncertainty box bounces around and is suddenly within IN RANGE. When that happens, your missile is fired. It's almost instantaneously. Within seconds, the target bounces around again, and it your missile is now out of range and it will die because it ran out of fuel.
I have even tried to restrict the range of the firing unit. That works, but it really cripples the firing unit, especially with air-to-air missiles.
So, if the devs could make the firing aircraft a little less trigger-happy, that would probably solve the problem. Otherwise, like you experienced, a lot of missiles will be wasted.
Somewhere in the Tech Support section I reported this a couple of times, but as far as I know it was never addressed, as evidenced by your report.