I'm trying to merge two edges that are converted from nurb curves. I've combined mesh and when I try to merge them I get the result below. I've cleared history and tried to open the options box for merge edge but nothing opens. All the edges are lined up, no missing loops and like I said I get the dimple result pictured below and overlapping cross loops as well. Any help would be appreciated, thank you. Maybe close the file and reopen or even import it into a new scene if it persists?

I added another image I still can't figure it out. All the edges are lined up, all curves are deleted even. There are no double edges, they simply won't merge. I deleted faces and edges to make new ones and extruded two new sets of edges and faces and those will not merge either.