Pipe Seam Issue Not Allowing Split

I am using pipe command to make a groove on a surface. The first 2 split without issue, but this last one will not split. It says it does not intersect.

In this screen shot I highlighted a curve created by Curve Between 2 sets command. It is clear that Rhino doesn’t think there is an intersection along one side of the pipe.

I try to use “SRFseam”, but I cannot select the seam. I can’t find any seams in my drawing that I can select or modify with SRFseam.

Any ideas?

I guess I can split the pipe down the middle, and mirror the side without a seam to the other seam? I really shouldn’t have to invent weird techniques to make a simple split!

Ok, that worked. Splitting the pipe and mirroring it to eliminate the problem seam, that is. I thought of it while I was typing before.

If the pipe is closed (has end caps), it is a polysurface, you can’t move the seam in a polysurface. You can explode it, delete the ends, move the seam on the pipe surface and then Cap to remake the end caps.

Oh, that makes sense. I’ll try that next time.