Were you in high sec, low sec, nul or a worm hole?
If you were being attacked at what range did the attackers activate the first "offensive" module or fire at you?
Did you or they have any ewar active?
Were you in a mission, site, anom where your targets would be NPC"s?

Since we lack this information I can only go with the most basic answer so here goes.
Auto targeting, AKA friend or foe missile are bound by aggression mechanics to prevent you from firing on someone or something that is not a legitimate target.

By design and requirement they are retaliatory in nature, meaning they will not fire until the other player has done something that gives you rights to shoot at them. Alone this could be all that is needed to explain the behavior you are experiencing.

Targeting you is not considered an act of aggression and so auto targeting would not target and may not even fire.

Remember that the maximum range of a missile is not connected in any way to you or the missiles targeting range.

I wouldn't say useless.

Jonny Pew has a nice Youtube video on using the auto targeters in Hi-Sec combat site farming. They are something of an AFK kind of combat farming. You warp in, the ship blasts everything around it and then you pick up the goodies and warp off to the next site.

It looked very similar to doing the same thing with smartbombs but with those you had to warp on top of the spawn point and keep an eye out for anyone warping into the site because if you hit them with a smartbomb blast, you'd get a visit from Concord.

I think you can still 'target' something and fire the missles manually, I know you can with an auto targeting system and using guns. I don't know if it's the same mechanism.

You cannot. I was trying this in the original scenario. Couldn't shoot (even locked on) until fired at first...something like 10-20km out of my 102km range.

Yup, the point of the FoF missiles is to shoot back when you are jammed and cannot lock on to anyone. By definition, the guy(s) jamming you have already committed aggression and thus will be targeted by the FoF missiles.

In practice, "bring a friend", "primary the ECM jammer", and other tactics work much better than "bring FoF missiles", so, as indicated above, they're only used in very niche situations.

Ahhhhh. That makes perfect sense. Yes, that most basic answer is the one for which I was looking. I'm sure auto-target missiles have their niche, but this particular drawback seems like it would make them damn near useless.

Thanks for the reply.

If jamming is an issue in missions you need to be in a Marauder and problem solved. Marauders with bastion running are immune to all e-war except energy vampires and energy neutralizers.