Can't unroll mirror surface

I can’t find out why the mirror part won’t unroll and rhino stops when I try it, what am I doing wrong?
uroll mirror part.3dm (449.4 KB)

Hi Edward - I see that, thanks… not sure yet.
@E.O.Stam - UnrollSrf does not like that the mirrored surface’s normal is not the natural one - use Flip on the surface and it will unroll.
Pretty sure we can fix this, thanks for the heads-up.
RH-82481 Unroll mirrored surface error

(btw, the I see mirror plane is very slightly off of the X axis - you might want to check that)