Layer flattens automatically after Rhino 7 update

I am working with a large 3-D model of a New York City neighborhood. Before the most recent Rhino 7 update, the topography contours were arranged according to their height; now the Contour layer is flattened. Every subsequent download of the model flattens this layer automatically.
The same happened to one of my students (contours were 3-D, now after the update, they are flat).
Where might the problem lie? Thanks for any insights!

Hi Heidi -

I’m afraid there is not enough information in your post to be able to guess what’s going on.
Are you simply opening a .3dm file?

Hello Wim - thank you for your reply.

Yes, I am simply opening a .3dm file, and whereas the contour lines (on a single layer) would previously be at their respective levels in the Z plane, they are now flat. Fresh downloads of the file give the same result.
I am downloading files from the following site, and specifically the file under Manhattan - MN CD 12 Inwood, Washington Heights:


Hi Heidi -
Just to make sure, I opened that file in Rhino 7.19 and all contours appear to be on the same height there as well.

I remembered that those files were discussed here before and it seems like contours are always flat but might be on different heights in different files - see:


Note that this file also opens in Rhino V6. The buildings are in 3D, but the contour lines are indeed all flat, although they’re not on the 0 plane, they are at 7.49 for some reason… It is the same in V7, so the Rhino version has nothing to do with the contours being 2D.

Thank you so much for checking into this and for your feedback!

Thank you so much Wim for your feedback and additional reference!