I keep seeing customers declaring what Glowforge does and does not support, but I cannot find any statements from people who represent Glowforge. Are you authorized by Glowforge to make this statement?
Based on my software development experience I think it is a rash assumption to decide that the issue is with the Materials Manager.
Glowforge benefits greatly from the existence of the Materials Manager and it would be prudent to test changes they make against materials created there to make sure they do not break it unless absolutely necessary.
I believe the safe assumption is that Glowforge testing process does not take into account materials created with the Materials Manager. Hopefully Glowforge is working to figure out what is broken and what the fix involves.
Unfortunately the Glowforge model does not afford me the luxury of opting out of this recent change and allow me to use the previous version of the software that works for what I want to do.
This complete lack of control is a recurring frustration and should be a red flag to people considering a purchase of the product.