Please disregard my previous reply @KPeter - I figured how to add the plane correctly to mimic the result you got.
However, I am now facing another issue when using the loft tool then subtracting it from the lug. One side is higher than the other, which becomes uneven from the side profile. Also, when looking at it from the front profile, there is a small dip at the top and not straight. Everything else seems fine, this is now the only problem. How can I have it align correctly so they are both the same height on both sides with a straight top?
Here is a picture of a watch lug that I am trying to model: 
Pictures of uneven lugs when using loft/subtract method as suggested.
