I'm not aware of any such bug. Might be another quest interfering. Try looking in all the other rooms. If you're still stuck then you'll need to ask on our Discord.
Had the same issue today, and indeed this is not a bug. I was supposed to spy on Cassandra, I was redirected to Debbies room which was ... empty.
Looked at the code, I felt stupid. What happens is that dnir == True, in which case we cannot reach cass_flirt_debbie2. Because in fact she has a homework ongoing in amys room (staff_training_02). So indeed both quest lines cannot happen in parallel. I set dnir = True to lift this temporarly.