A visible seam is observable during SubD operations on a boolean cut.

Prior to applying the Boolean I created supporting edge loops which are not approximately\* in line, they are exactly\* in line, ie. mesh topology looks so good it brings a tear to the eye.

Despite this, for the past 2 weeks this issue persists. Weighted normals and proximity loops help the overall shape, but only minimize this particular effect. A blend file should be attached. Picture illustrates issues.

[![](https://blend-exchange.giantcowfilms.com/embedImage.png?bid=VpLwZPyX)](https://blend-exchange.giantcowfilms.com/b/VpLwZPyX/)

[![Issue](https://i.stack.imgur.com/piWnf.png)](https://i.stack.imgur.com/piWnf.png)
[![Edge Norms](https://i.stack.imgur.com/K8o7w.jpg)](https://i.stack.imgur.com/K8o7w.jpg)
[![Vert Norms](https://i.stack.imgur.com/1FRhT.png)](https://i.stack.imgur.com/1FRhT.png)

Is anyone able to identify this issue, and what the solution is?