I sent my sim to Uni for 2 terms, 36 credits with an aptitude score of 400 in Fine Arts, meaning I started with 18 credits. After the first term ended my sim was on the Dean's List but I did not recieve a report card and her credit progress remained at 18. At the end of the second term, the same thing happened; no report card, no progress. I saw that a lot of other people were having the same problem but none of the suggested solutions worked for me, so here is what I did to fix the issue in my game. You need the MasterController mod from NRaas.
1. Save your game with a new name immediately after finishing your last final exam.
2. Use MasterController-Intermediate-Career-Academic Degree and set it to however many credits you've earned.
3. You should soon get the popup telling you that your sim has completed their degree and the report card is coming. If you have the LTW Perfect Student, it should complete at around midnight.
4. Save again with alternate after the notice of an upcoming report card and if you don't get it by 10:00 a.m. Saturday, reload and try again.
5. After getting report card, save again with new alternate and if you're finished with your degree send your sim to the Stadium/Annex no later than 12:00 p.m. Saturday and wait for the push to Graduate at around 1 p.m. Don't queue it yourself, and don't cancel it even if it hangs for a while. For some reason it takes a while for the sim to change to robes but if you cancel and re-queue, IME, it just doesn't work at all. If you miss graduation, reload and try again.
6. When you get the notice that you're returning to your homeworld soon, make sure that you're at your home, preferably waiting near the curb and save again before the van arrives. It's best to have autonomy off so that your sim can't do anything to disturb the push to get into the van but if it borks, reload; try again.
Following these steps, I was able to get my sim her degree and back home safely without having to be too cheaty about it. I only applied the credits that had been earned but not given and the game took care of the rest of the steps the normal way.
