OCC: Bugged 3D modeling when adding fillet to revolved square

Problem description

FreeCAD version: 1.1 RC2 Can't create a specific shape (tried to create a random shape to learn the program) Shape has a hole in the surface

Workbench affected?

None

Steps to reproduce

Steps to reproduce:

1. Create 100mmx100mmx100mm cube
2. Start a new drawing on any surface of the cube
3. Draw a square of any size, one of the edges must touch the cube
4. Revolve 90 degrees
5. Fillet all 3 sides of that revolve where it contacts cube except the outer edge* (check screenshots)
6. Set fillet size > 5mm (10-15mm shows best)

FreeCAD-Bug.zip

Expected behavior

Successful 3D model

Actual behavior

Shape surface distorted

Development version About Info (in Safe Mode)

OS: Windows 11 build 26200
Architecture: x86_64
Version: 1.1.0rc2.20260108 (Git shallow)
Build date: 2026/01/08 12:03:27
Build type: Release
Branch: (HEAD detached at 0c7935c)
Hash: 0c7935c755bd9531f7061be31fab8788742a44b7
Python 3.11.14, Qt 6.8.3, Coin 4.0.3, Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, IfcOpenShell 0.8.4, OCC 7.8.1
Locale: Turkish/Türkiye (tr_TR)
Navigation Style/Orbit Style/Rotation Mode: CAD/Rounded Arcball/Window center
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Dark/
Logical DPI/Physical DPI/Pixel Ratio: 96/113.268/1.25

Last known good version (optional)