Offset surface failure

A command sequence I have used a lot in the past has suddenly started to fail unpredictably. Rhino Version 5 SR14 64-bit (5.14.522.8390, 05/22/17)
I intersect cut planes with a solid polysurface -> trim then pipe the resulting curves -> split the poly with the pipes -> shrink then offset surfaces for new closed polysurfaces. The atttached image shows the result as of today. What is causing this failure?

I have attached the model file. Happy for any assistance.
TIA Robb
fail.3dm (996.2 KB)

Hi Robb - checkin’ it, thanks.
@rcmcdougle - for now, it seems to help to: DupBorder, SimplifyCrv, Untrim the surface and retrim with the simplified curve.
-Pascal