after forum search i cannot figure out what happens.
I have bodies, use only "part design" workbench and did some boolean operations.
in the graph dependancy, some sketch are visible (at the begining), there is no error message when i double click on it for edit, but nothing is displayed in the screen, sketches seems empty but no message about it.
i checked visibilities in the graph, try to set all visible, take care about what is activated or not (body, etc...) but nothing. I guess it's related to boolean operations but dont know.
th new thing i used and is different from usual is starting from a reference plan from another body with the "create a new datum plan".
some sketches works fine for edit, other dont.
can you switch on the light in my mind ?


i attach my file and a screenshot to see wich sketches a talking about
My freecad version is :
OS: Ubuntu 18.04.2 LTS (KDE/plasma)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.
Build type: Release
Python version: 3.6.8
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: French/France (fr_FR)