I have all EPs and SPs. I tried starting the game with custom content disabled, loading the lot, saving it, then exiting to the neighborhood and reloading the lot again. Of course, it hasn't helped.
My Young Adult sims can only talk about college majors as long as they haven't chosen one. As soon as they pick a major, the option disappears.
Default Young Adults who Maxis already picked a major for still have the Talk.../About Major menu option. However, their speech bubble shows them talking about an undeclared major rather than their actual major. And if I change their major using either the phone or the computer, they lose the menu option too.
Also, my memory may be a little fuzzy on this, but wasn't there at some point (no later than Seasons) an Ask.../What's Your Major option? I don't have that with any sims.