i think i found it. by the time i realized my gun wouldn't pew pew, i was out in the field. single save, and recent. i was just by Caroline's house near the gate south on my way to do a quest to the south.
out of desperation i guess? i went back home and when i talked to the barrels to enter they replied "Spend some time by exploring" instead of "go home?" so i clicked yes, and it teleported me outside... where i already was. guns fully functional now.
my guess is that something borked a script that allows you to fire your weapons while in the field, and having literally no experience with this kind of stuff unless vicarious experience watching skyrim and fallout modders make fancy mods counts.
i'd bet that there's some sort of hidden Buff or Status that's applied to us when we exit the safehouse and go to the Field but the quest where we shoot down the boss in Her place borks the game.
Hmm... I think you discovered an interesting clue about this bug. You said that you tried to go back home and when you interacted with the blockade, it reacted as if you were home and tried to go out. And when we are home, we cannot use weapons. So if the game thinks we are home then it disables or doesn't enable weapons. Then this bug might be that the game, for some reasons, thinks we are home when we are out. I think you discovered an interesting point to help the developer understand the issue and solve it, thank you. :-)
Also, this bug occurred to you elsewhere than at the botanical center so thanks to your report we now know that this bug doesn't occur only at this area.
I didn't encounter any issue with the boss fight in Caroline's house, it occurred only at the botanical center for me so it might not occur at the same location for everyone.