You have 2 edges against only one on the surface so.. :) and Micheal is always more speedy than me! :)

And because i don't remember the Merge method :)
so my long method :)

Move Extract the 2 edges + the close circle Edge
Join the 2 edges it's now 2 curves !
Straight Loft the 2 Curves
Replace this repair against the false original



Here with Blend no problem after repair!