Are you testing the PFE with all appliances discharging air to exterior? Example:Dryer, range hood, bathroom exhaust fans, water heater running, furnace blower on and off. Are the heating and cooling units in the attic of the house? I have found these to really depressurize the basement. Sounds like you may be loosing PFE. I like to see -0.02 "WC or - 5Pa at all test holes. What is the pressure difference between the basement living area and the exterior? Is it possible there is a footing between the closet and the owners family room restricting flow? How is the owners family room and apartment living room stitched together? What is the pipe size and cfm you are moving? Have you tried flipping the fan and run a crm to see what radon levels do? Run a short test and stop test if levels rise higher than starting levels. Are there any exterior structures, patios or steps that could be causing an issue? I would say its probably not the ideal location for the suction point but I understand how some clients do not want it visible in the living areas. I would like to see a suction point mid wall on one of the long walls of the basement or next to a plumbing riser. Just my opinion.