Are you playing multiple households at the same time in Uni by switching back and forth between households during a term?
I have all the dorms and houses in Brichester full so I too have multiple households attending University. I play 1 household for a full term, start to finish, before switching households and all my sims get good grades. The only time I have ever had a sim fail was in the beginning when DU came out when I left a household in mid term to play another. When I got back to the first household, every sim in it had failed the term. I had mistakenly thought that DU worked like it did in TS2 where a term did not progress for a household unless you were actively playing that household but found out the hard way that it doesn't. So now I play each household for the entire 7 day (long life, 28 day season) term and I have had none fail. At the end of the term, after the grades come out, I decide if I want to play that household for another term or play another household for a while before returning to them.
Hope this helps.
