It took longer than I expected to get back to you, but here’s what I’ve found.
We were able to narrow the differences down to the plain text SVG code coming out of Illustrator. The differences between a 1" by 1" square, created independently on a Windows laptop and MacOS laptop seem to be causing the trouble.
Here is the SVG code from a square created in MacOS on the current version of Illustrator. This SVG code can be pasted into the Design Library and opens as a 1" by 1" square as expected. <svg id=“Layer_1” data-name=“Layer 1” xmlns=“http://www.w3.org/2000/svg%22 width=“1.01in” height=“1.01in” viewBox=“0 0 73 73”><defs><style>.cls-1{fill:#fff;stroke:#231f20;stroke-miterlimit:10;}</style></defs><rect class=“cls-1” x=“0.5” y=“0.5” width=“72” height=“72”/></svg>
Here is the SVG code from a square created in Windows on the current version of Illustrator. This code, when pasted into the Design Library, opens to a square that is approximately .75” by .75"<svg id=“Layer_1” data-name=“Layer 1” xmlns=“http://www.w3.org/2000/svg” viewBox=“0 0 73.13 73.13”><defs><style>.cls-1{fill:#fff;stroke:#231f20;stroke-miterlimit:10;}</style></defs><rect class=“cls-1” x=“0.5” y=“0.5” width=“72.13” height=“72.13”/></svg>
The MacOS version is defining a width and height that can be applied to the layer; this is missing from the Windows version. This means there is no reference point to use when the Glowforge app scales the design. There are ways we try to scale appropriately in our software when this information is missing, but that’s dependent on the other information present. For instance, if the same SVG were exported and then uploaded, it would include information that the file came from Illustrator. This would fill in the blanks our software needs to understand the default dpi being used by the program, and how we can calculate that to match our app’s display.
I’ll raise the concern with Adobe, as well, but for now without width and height being defined in the raw Windows SVG code, there’s a high probability that the Glowforge app isn’t the only program unable to match the dimensions to the dpi from Illustrator in Windows when using this method. If you’d like to add another voice to that concern in their forums, that might be helpful.
Thanks so much for all the work here to get more information. Right now, there isn’t a method that can help this exact workflow succeed without rolling back your Illustrator version on Windows, but I hope this helps you understand a little more what’s going on.