Applying these filters does nothing to change a monoline, is there a good way to troubleshoot this issue?
BroadNibber is currently incompatible with Glyphs 2, it should work in Glyphs 1.4.x.
The Make Stroke option of Offset Paths works in both G1 and G2 for me. Which app/OS setup do you have?
OS X 10.10 Yosemite
Offset Paths is now working in G2, is there a way to keep original paths?
Glyphs 1.4.3 is not working at all in 10.10 (windows freeze).
Activate Glyphs > Preferences > Updates > Cutting edge and update to the latest 1.4.4 beta.