I'm struggling to find out why I have this pinching. All I could think to do is merge vertices. It's probably one of those situations where it's impossible to give a definitive answer but I thought I'd ask anyway. It's not going to stop me moving forward as I can always come back to it. Thanks.
Hi Roger,
From the screenshot, I'd also say double Vertices (adjust Merge Distance if needed).
Might be worth making sure that your Normals are consistent, but I don't expect that's causing this.
If that doesn't help, check for interior Edges or Faces (switch to Wireframe Mode to see them).
What are your settings on the bevel modifier? It could be that you're just around the angle where it kicks in and I've had that give me issues in a situation like this. If you don't find double vertices or interior stuff I'd go through the modifiers one by one and toggle things on an off to see if one or another has something to do with it.
What Sascha says its one of the things I do. I turn off all the modifiers and see if the issue goes away, then turn them on one by one and when the problem pops up, then I know which modifier could be causing it. But sometime that goes along with something about the geometry.
One way to tell if there's something wrong in the geometry is to select a vertex and with G move it around, just to see if something pops up. You can notice you have an interior face or double vertices. Another thing is to hit Control + R and place your mouse over the geometry to see if the loops flow none stop, if they stop abruptly over that area, you know there is a problem and you can go in an investigate.