Try different times of the day. I got stuck with Sarah's on day 114. Had to find it at night.
The exact conditions are:
"Visit Mia in in her room after day 32."
"Visit Emily at her home... after day 52.",
"Go to the university at night after day 55.",
"Check the school pool to see if the plan worked."
"Try the university after day 58."
The test subject is Chloe and if she isn't there yet it means you're missing certain quests. Basically you have to complete tasks in the the journal starting at the lowest day and you'll never get stuck and everything will flow 100% naturally.
All tasks trigger any time of the day unless specified.