G4: Re-Interpolate does nothing on a backup layer (worked in G3)

Glyphs
1

In Glyphs 3 I could right-click any layer and choose Re-Interpolate to get a reference interpolation next to the master, without touching the master. In Glyphs 4 (version 4.1.1, build 4108, MacOS Golden Gate) the menu item is still offered (screenshot attached), but nothing happens. It only works on the master layer itself.

Is this an intentional change in logic from G3 to G4, or is it a bug?

Thank you,
Ales Micka

Snímek obrazovky 2026-10-24 v 9.53.03
Snímek obrazovky 2026-10-24 v 9.53.03694×722 95.5 KB

2

It doesn’t work for me in Glyphs 3, either.

3

Here’s a video of how I use it in my workflow in Glyphs 3 (3.4.1—3436):