Hi Tony - it looks like this is actually the result of a bug fix where MoI was handling the "outside" direction of open surfaces differently than Rhino.

I noticed some inconsistent handling between MoI's treatment of open surfaces in certain cases compared with Rhino (it depended on the ordering of some of the surfaces), so with that last Jan-21 beta I changed this so that MoI would handle the orientation the same as Rhino.

I guess that I should have tried to detect if the file was written by an older version of MoI and maintain the incorrect orientation when reading it in.... But I guess it may be too late for that now.

I should be able to add a Flip command in for the next beta that can be used to solve cases like this, I will give that a try and see about posting back a flipped version here.

- Michael