University commons food stand not working?

Clearing the cache files and repairing the game doesn't help?

Sometimes it's just closed; I presume it's on some sort of schedule but I haven't worked out what it is.

Yeah, you might just be checking when it's closed like @Simpatsyann said. It's open three times (breakfast, lunch, dinner) between 7am and 11pm. It closes for a while between mealtimes.

I just had this happen, waited hours and absolutely no one showed up. Go to build mode sell off the old one and place a new one. That did it for mine. Best of luck!