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.