ok figured a partial fix to getting detention. I got caught in the morning class, then left to the Danger Room for an afternoon session, and Emma was still in the classroom and commented about how (paraphrasing because I didn't save before hand) "skipping detention is bad, you're a bad boy arent you?" or something similar, but led to me being able to feel her up and get her number.
Getting caught and asked to remain for detention, or for that matter anything regarding afternoon class seems to 100% guarantee Emma leaves class and no amount of leaving/returning gets her to reappear in the evening/night. So there seems to be a coding issue somewhere in regards to attending afternoon class, that puts Emma in a limbo state that's particularly frustrating if one hasn't gotten her phone number yet.