If you visit the "Missions" in the sidebar, do you see Homework#3 listed as green? Quest 4 should be available automatically once you finish that. If it's there and you still can't start when visiting Scarlett could you share a save file with me and I'll look into it?
Thanks for the save, I found the reason from another file but I tested yours too to verify. Quest #4 is available on day 8 or following that, sleeping 2 days will get Scarlett to give you the quest.
Got a save file and found the problem. Quest 4 is available only after on day 8 and onwards which was unintended. For now just sleep until day 8, in another version I'll remove this limit.
