Snapping project on self not working after knife

Hello all,
modeling:
I’m making a building in 3D: the scene is composed as it:
1 object is my building
and 5 planes with textures are mapped with ortho plans by map.

When i’m in Edit mode on my building, the 3D snap is ok, 2,5D too.
I cut the mesh with Knife , then the snap isn’t working on my building.
The snap is not working on project on self ( even if I toggle this option).
but the snap is still working on other object: It means the project on self is broken after a Knife on my scene.

To make it working again I have to isolate my building then unisolate and thats fine.
It would be good to fix it :smiley:

greetings
Fred