I was attempting to investigate techniques of improving the robustness of Shell features.
In this part I ran Modify>Utilities>Make Uniform on the T-spline body.
The sliver face appeared on moving the time-line back to the Split feature.
(and I had to edit the Shell feature and decrease the wall thickness - the opposite of my design intent)
Solved! Go to Solution.
Solved by innovatenate. Go to Solution.
Well, still can't attach *.f3d files here through IE, so had to switch over to Chrome.
Thank you for reporting this, I've submitted this issue to development for further review.
I note that if I Edit the first Form, run a Sculpt > Modify > Utilities > Repair Body command to repair the star points (red), the sliver face will resolve itself. I suspect the sliver is a result poor b-rep geometry generated by star points in the form.
Let me know if this helps or if you have further questions.