Hi @HayleyHolli,
Can you share a bit more context? In your final list, do you want only contacts who are in all three lists? If that’s what you’re expecting, what is happening instead? Can you please share a screenshot of the filters of the final list?
Just to confirm, if you want only contacts who are members in all three lists, have you used the AND operator? (is member of MTKG - BASE LIST - Prospects AND is member of…)
Best regards