So I've been playing F2 for a few weeks having a blast. Today, at some point in my play session, something has occurred which is preventing any NPC/monster from attacking me. For example, after fixing the air purifier in Broken Hills, I wanted to mop up the remaining ants and scorpions, but they won't attack. I can attack them, and then they'll fight, but they won't attack me. I brushed it off and went to New Reno - same thing - no one will attack me, no matter what dialogue options I choose, etc. The dialogue just terminates and then nothing happens.

Anyone have any ideas? I'm concerned because this may "break" parts of the game, or at least make it artificially easy, since I can go places I"m not supposed to be able to without being shot up. I'm running the recommended mods except restoration project. I've googled but haven't found anything useful.

Same here. But for me, it's even worse. I can't press the "attack"-button, so enemies can't attack me and I can't attack them.

EDIT:
I don't know if you allready have found an answer on your problem. But for me, it was a cprippled arm. Apperantly, when you have a crippled arm and walk around with a two handed weapon, not only can't you attack enemies, it's allso the same thing the other way around, enemies can't attack you. So, you're in a semi-god mode as you still can take damage from other stuff like traps.

One more thing. Doctors don't fix crippled limbs as long as you have 100% health. But you can use the doctor skill on your self until you succeed.

Huh, that's a cool bug. In all my time of playing Fallouts, I've never encountered it (but then again, even when my char had a crippled limb, I got it fixed ASAP).
But good to know such an error exists, so thanks for sharing!