I can't open your file future version you do it under which version?
I'm on SW2012 sp 3 premium
It's true that if the part is made in sheet metal from the beginning it works with my version, the sketches follow the faces
but if you play with the unfold and fold a fold functions
At a certain point the sketches are duplicated before and after the fold or at least the sketch disappears which loses its origin from the front but no plane
you have to unfold the piece but not fold by fold
Things are not well optimized in there it's not 100/100 efficient
and if you start from a volume that you convert into sheet metal it doesn't follow the faces
I just tested on a 2012 at work and it works! The sketches of the piece you posted follow the unfolding well! Weird that there are bugs from time to time! A+
I don't understand, I have no problem with this type of sketches.
I use the faces of my sheet metal piece directly to lay my sketches, and they follow the unfolded correctly - fortunately, everything goes through a laser -