instance.interpolatedFont.masters[0] returns empty master

Hello, I am trying to work with instance.interpolatedFont in order to circumvent some annoying bugs in the addAsMaster() process.

interpolated = Font.instances[0].interpolatedFont


What I get as my added master is simply an empty master; all glyphs are empty. Trying print(interpolated.masters[0].glyphs["a"].layers[0].shapes) gives me <GSPath 39 Nodes>, so there is something that gets lost along the way. Any ideas? Thanks!

Adding the master is just doing that. The layers in each glyph are not copied over. Can you try:

interpolated = Font.instances[0].interpolatedFont


print(interpolated.masters[0].glyphs["a"].layers[0].shapes should not work. A master has no glyphs.