in the attached design, I get an abnormal behaviour when trying to fusion items.
for instance, fusion004+fusion001, it's ok, but fusion004+ any other, there is an issue.
Maybe it can come from the item wall002_rdc, but I don't know what to do to repair this.
Wall002_rdc is a fusion of several other parts... not neccesseraily on grid

OS: Windows XP
Word size of OS: 32-bit
Word size of FreeCAD: 32-bit
Version: 0.16.6612 (Git)
Build type: Release
Branch: master
Hash: 18f0cc634665e15f5191dbfa9ea980a16e25ad26
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17