Struggled to Inset – Edge Rail?

HI Roger,

I don’t think your issue has anything to do with Edge Rail (which I, I must confess, have never used). What Edge Rail does, is best shown in an example; the left Inset is ‘normal’ (slides the new Vertices along the Normals) and the right Inset has Edge Rail enabled (new Verts slide along existing Edges):

Now, in your first image, Boundary is un-checked, meaning it doesn’t Inset at the Boundary (where Edges only connect to 1 Face each)…that looks completely normal to me.

In the second image, Boundary is still un-checked, suggesting, that you have created some double Vertices at that original Boundary Loop, thus enabling the Inset without Boundary Checked. Like I said, Edge Rail has nothing to do with whether the Faces at the Boundary get Inset or not.