Hello all, I seem to be having a problem speaking to vendors included in any mods.

Whenever I speak to a vendor that comes with a mod, I don't get access to the dialog screen that allows me to interact with them. I can't ask them what they're selling, I can't say goodbye, nor can I do anything else. All I get is a casual greeting from the vendor, as if I'm just walking by them or something. It's frustrating

The mods that I associate with this problem are Leveler's Tower, Calling Card Fence, the Undercity, Shady Fences, Riverwood Barber (each of those mods include vendors, in which I can't interact with), and Live Another Life. I have a hypothesis, however: I used Live Another Life to start from a new point, and at some point (I haven't done this yet, however) I'll have to manually start the main quest, and the lack of main quest might be (for some reason) inhibiting me from accessing these vendors. I say this because I tried all of those mods on a character that has completed the main quest, and they all worked fine, but when I try them on my new, Live Another Life character who hasn't started the MQ yet, the vendors don't work in the slightest.

Am I close in my hypothesis? Does anyone have an idea?