Yeah, there seems to be something weird going on for some people with certain factions / certain guilds. I'm starting to suspect there is something else going on w.r.t. this, e.g.

A maximum number of each guild type available in a game, i.e. if there is a max of, say, 20 thieves guilds, and your opponents already have them all, then youre never going to get one regardless of what you do.

or

Some factions (or maybe just specific settlments) just dont get access to certain guilds. Pretty unlikely though IMO, cos i've seen people complain that, say, they cant get a theologians guild in caenarvon as the english no matter what they do, and i know that i've done exactly that in the past.