Chamfer/Fillet: "There are no suitable edges for chamfer or fillet" on suitable edge

Problem description

Trying to chamfer or fillet the following edge at the boundary between two lofts in piecewise.FCStd fails:

Notably, making the first AdditiveLoft into a ruled one makes the same edge work fine.

Workbench affected?

Part Design

Steps to reproduce

1. Select AdditiveLoft001.Edge9
2. Chamfer/fillet it

Expected behavior

Actual behavior

Fillet: There are no suitable edges for chamfer or fillet

Development version About Info (in Safe Mode)

OS: Void Linux (KDE/wayland)
Architecture: x86_64
Version: 26.3.0dev.20260728 (Git shallow) AppImage
Build date: 2026/07/28 21:59:12
Build type: Release
Branch: (HEAD detached at 63af5cb2f)
Hash: 63af5cb2f3dbb2b4c7333f6d220b03e05bf92f99
Python 3.11.14, Qt 6.8.3, Coin 4.0.10 (bundled), Pivy 0.6.11 (bundled), Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, Clipper2 , IfcOpenShell 0.8.0, OCC 7.8.1
Locale: English/United Kingdom (en_GB)
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Dark/
QPA/File dialog/Color dialog: xcb/via Qt/via Qt
Navigation Style/Orbit Style/Rotation Mode: CAD/Free Turntable/Drag at cursor
Logical DPI/Physical DPI/Pixel Ratio: 96/92.6073/1
OpenGL version/vendor/renderer: 4.6 (Compatibility Profile) Mesa 26.1.5/Intel/Mesa Intel(R) Arc(tm) B580 Graphics (BMG G21)

Note

This is not even continuity shenanigans, as s = Gui.Selection.getSelection()[0]; [e.Continuity for e in s.Shape.Edges] + [f.Surface.Continuity for f in s.Shape.Faces] returns a list of only "CN" when AdditiveLoft001 is selected.