Yet another trim mystery

Rhino Rhino for Windows
1

Can some forum detectives spot what’s wrong here, since Rhino isn’t telling me…

image
image1265×1002 196 KB

Red managed to trim green, but green couldn’t trim red. I created the blue line to see if that would work to trim red but that also failed. What am I missing?

trim-fail-mystery.3dm (222.3 KB)

2

Green trims red for me using Version 8 SR4 (8.4.24030.15001, 2024-01-30).

Command: Trim
Select cutting objects ( ExtendCuttingLines=No ApparentIntersections=No Line )
Select cutting objects. Press Enter when done ( ExtendCuttingLines=No ApparentIntersections=No Line )
Select object to trim, select pressing Shift to extend ( ExtendCuttingLines=No ApparentIntersections=No )
Splitting… Press Esc to cancel
Select object to trim, select pressing Shift to extend. Press Enter when done ( ExtendCuttingLines=No ApparentIntersections=No Undo )