I have an issue with the Add operation in comparison to Illustrator. As of now, I don't believe there is a feature that allows us to select by fill or color, this prohibits me from being able to select only the black infill and then add or merge them together as one shape. In Illustrator, I can select by fill color, select "unite" in the pathfnder window (which I believe is the equivialent to "add" in affinity) my design comes out perfect. With affinity, since there is no option to select on by fill color, I have to select everything, then select "add" which fills in portions of the object with solid black.