You'll need to describe the layout where they "show up anyway". Is this a layout based Product, Element_Nav2 or some other table occurrence? Are they showing up in a portal? If so, a portal based on what table occurrence?
Note also that a relationship cannot match null values in the match fields so you will also need to assign a value (perhaps 0?) to the fields where the match field is currently empty.
The layout is based on Element_Nav2. No portal.
I'll go through the 272,000 records and change any empty values to zero first and give that a try.
The null values are not the immediate problem. Null values don't match to anything.
Given the fact that you are looking at records from Element_Nav2 on a layout based on Element_Nav2, you will be able to see all records from Element_Nav2 no matter what relationships you define for that table occurrence. The portal is based on the table, not a relationship. A portal to those records, on the other hand, will use the relationship between the layout's table occurrence and the portal's underlying table occurrence to limit what records are currently visible.
You can also perform a find to limit what records in the layout's table are visible.
I replaced the 5,630 null values in the PRODUCT table with "0" and the same with the 272,000 null values in the ELEMENT table. Also added a Boolean calc so those will always be 0 or 1. Success. It now shows no records when I uncheck the 2 values that were "1" from the Add2Nav field.