It seems you've contacted Tech Support via email. I'll capture the workaround that we provided you over here for everyone else's reference.
The mentioned hgexport error shows up in both R2020b and R2021a. Here are two workarounds:
1. Try saving the figure in other formats such as PNG, if that works for you.
2. Explicitly set the figure's renderer to OpenGL before saving it. This would force the file to show an embedded image. This embedded image won't scale/resize as well as the other EMF files but it will allow you to use the same format. Run the following line before saving the figure to set the renderer for the current figure:
set(gcf, 'renderer', 'opengl')