Can't Live on Campus?

Any chance she's pregnant? (probably mod related) or are you tring to move her with a pet or younger sibling? all sims on campus housing must be enrolled in the school, and since pets and kids can't be enrolled in school, they can't come with when you go to campus housing. It will also deny campus housing to pregnant sims since the baby will be born during the term.

Also double check the lots that you didn't turn them into something else at some point.

Here's another thread where the poster discovered the problem was a mod.

https://forums.thesims.com/en_us/discussion/995229/move-to-uni-housing-is-not-an-option

"DaWaterRat;c-18249522" wrote:
Any chance she's pregnant? (probably mod related) or are you tring to move her with a pet or younger sibling? all sims on campus housing must be enrolled in the school, and since pets and kids can't be enrolled in school, they can't come with when you go to campus housing. It will also deny campus housing to pregnant sims since the baby will be born during the term.

Also double check the lots that you didn't turn them into something else at some point.

She's definitely not pregnant, as she just aged up from a teen literally the in-game hour before and has not woohooed or tried for a baby. Also, I do not use any mods at all. She lives with her brother and parents right now, but I would not be attempting to move any of them. She got accepted to college (put in her application a couple of days before aging up) and is trying to use the computer to enroll. She can chose her university, her major, and her classes, but when she gets to the housing selection screen, the only too options are "At Home" and "Off Campus". None of the dorms are listed.

"simgirl1010;c-18249529" wrote:
Here's another thread where the poster discovered the problem was a mod.

https://forums.thesims.com/en_us/discussion/995229/move-to-uni-housing-is-not-an-option

While I don't have any mods, I did clear my cache as advised in the thread you linked and that seems to have worked!

Glad it worked!

Glad clearing the cache fixed it @Kraylessa :)
@Future They will be living in the dorm and not in their house any longer at all. Once they are moved into university housing, you can move another family in to the old house or delete it. Also, if you move another playable student into the same dorm, that student will join their household and you'll be controlling all three.