As you can see in this image, the correct layer.PlotColor.Name shoud have been ‘Red’, but it’s returning 'Blue" instead. However, in Rhino 7.3.21039.11201, this problem does not happen.
To me, this assertion returns False as it says layer.PlotColor.Name == ‘Blue’ for some strange reason.
If I follow te same code in Rhino 7.3.21039.11201, the assertion returns True
Colors in .NET are not quite the same as color on openNURBS, which is what the Rhino3dm.py is based on. Our ON_Color class defines alpha=0 as opaque, and System.Drawing.Color defines alpha=255.
The code appears to be doing the alpha conversion. So I’m not quite sure what is going on. So I’ve logged the issue so we can look into this.