why?Pack Faces in SubD does work

why?Pack Faces in SubD does work!

test on Rhino 7 SR6 2021-3-23 (Rhino 7, 7.6.21082.03001
and rhino8wip[Pack face in SubD does work

Looks like it’s due to the creases. I believe the packing is what would happen in ToNURBS and the creases would be areas of positional continuity in the resulting PolySrf. That’s my guess as to why it works this way with the face pack coloring which is a preview of that process.

What is it you’re trying to do here? A custom UV unwrap would keep it as one island.