The requirement for this event is Bandit's camp morale more than 25, and in Northcrest quest, you need to do in the green way which Bandit's camp doesn't get rid.
I think you have enough like for him. If you said you have camp's moral (not Bandit affection, it's not the same thing) more than 25 and Green ending in Northcrest conspiracy event, there should be Belly fun appear in talk option.
Bandit camp morale is 90, I have the green ending on the Northcrest Conspiracy, Harold at 35 like and. . .no belly fun option even after sleeping with him again. I'm so confused