Modular variable font – weight with virtual master

Hello, I tried to reproduce Mekkablue’s neat little trick seen at Typelab .glyphs Crit Session. That is, create a variable with just a weight axis, using just one master and one virtual master, the later set only to the base module glyph; see from 1:20:51 - YouTube.

I set the instances with the Insert Instances script.
But, as with Mekkablue live on stage;) it doesn’t work for me either. Instances appear in preview alright, but don’t work in Font Gauntlet or Fontgoogles either. Also tried to use a non-standard virtual master name, “Boldness” instead of “Weight”. What did I set up wrong?

Thanks a lot, and congratulations on v3.1!

Set the _part glyph to export. Then it will work. I’ll check why it doesn’t work otherwise.

Aaaa… Yes, it’s working!
(What a simple thing, like “elementary, my dear Watson”)
Thanks a lot, it will save me to set up two additional masters in a modular project