I know you're done messing with this, but when you said "I cannot add edge loops any longer", that sent up a red flag for me.
That doesn't just happen for no reason. If you can't add an edge loop, you have some disconnect in the continuity of your topology such as an n-gon.
I know I'm going into TL;DR territory, but I actually might be able to tell you exactly what was wrong without even seeing the .blend file -- You said you used dissolve, right? Well, if you use any of the newer commands that cause n-gons (such as dissolve, or filling a face across more than 4 vertices) and then you use old vertex connect techniques such as selecting two verts and pressing f to fill the edge, you will wind up with an n-gon with a non-manifold edge floating on top of it.
That would easily account for this, as there is no reliable way to know how any n-gon will triangulate upon usage in a game engine. The single edge wouldn't appear at all since vertices and edges have no real thickness.
I've done this more times than I'd like to admit -- try to get used to filling large gaps with ngons and using the knife tool (k) and vertex junction (j) to add in more edges.
PS: The camera didn't look right with all that shine anyway. This clearly happened for a reason. Hehe.