Hi, after I finally switched to Glyphs 3 from Glyphs 2 + fontmake, I’m struggling with variable font export.
Before exporting the final font, I generate the Regular+Italic masters from instances, which I then use to set up the font origin to Regular (when editing, I have only Thin, Black, Thin Ita, Black Ita masters and a bunch of brace layers). But the exported variable font includes an extra style (13 styles instead of 12). As soon as I set the origin to Thin, everything is OK.
Am I missing something obvious? Missing parameter? Any ideas appreciated 
OK, just found the problem.
Before generating the Regular master, the weight axis looks like this: Thin 100, Regular 350, Black 900 (+some instances in between)
The Regular instance coordinate is 350 – axis location parameter is 400. The generated Regular master coordinate is 350 – this results in two aesthetically identical styles present in the variable font – but with different parameters. When I remove the Axis location parameter, everything works. Except Regular is now 350, not 400. So I have to change Regular weight coordinates to 400 and re-calculate every instance between Thin>Regular>Black…
In short: You can’t use the Axis location parameter (with a different number than the actual master location) for an Instance that represents Variable Font Origin 
And it makes sense.
I wonder why you like you need those extra masters? It increases the file quite a bit and that undermines one advantage of variable fonts.
If I settle with Thin or Black variable font origin, I don’t necessarily need a Regular master. And you are right that the increased file size may not be worth it.
