EdgeContinuity - Cannot select the edge of the grey surface. Can select the edge of the blue surface. Occurs in both V8 and V9WIP.
Surfaces were created in V9 WIP. Grey surface created by Extend with Line option of blue surface, followed by ChangeDegree to 1 in the v direction.
EdgeContinuity Failure V8.3dm (1.9 MB)
It does seem to work here by left crossing window drag, or selecting the edge(s) on the opposite side of the surface.
Edit: in fact in some cases one of the edges simply gets occluded. Did you try this in Wireframe or Ghosted?
Looks like that is the problem. Selecting in wireframe works. In shaded I’m able to select one edge, then rotate the model so the other side of the surfaces are seen and select the other edge. Somewhere along the way one surface was modified to cause the overlap. I don’t remember encountering this problem before.