Problem now is that none of them (only 2 at this point) will sell to me. Caps are appearing in my workbench but I myself cannot interact with the merchants. When I try to one of two things happens:
1) I get the little blurb about whatever (i.e. "Crops been growing good lately") and that's it. I can try to talk to them over and over but nothing. No options. No bartering.
2) I get the standard "I need to trade a few things" interaction. Again, no matter how many times I reinitiate I only get the same interaction.
I've tried fast-travel and back & leaving the game and back. Also, I tried reassigning different people and storing the stands in my workbench and setting them up again. Still no sale, no service.