Glyphs3 Variable Font Interpolation Issue

I’ve noticed that in Glyphs3 the interpolation in the exported Variable Font doesn’t work like intended (and displayed in the Glyphs3 editor). In Glyphs2 the exported Variable Font works like intended.
The ZIP-file contains two videos showing both interpolation results: Glyphs2 & Glyphs3. (160.4 KB)

Is there something I need to do different in Glyphs3, so that I get the same interpolation results as from Glyphs2?

How does your designspace look like? Are the blue ones masters? Did you generate the VF with glyphs? Have you tried other ways of generating fonts, like fontmake?