Problem with shadow (dark areas and corners)

Hi everyone !

I just started a new archviz project, a simple hallway to test the potential of that soft.

I’m using 3dsmax to create everything and my scene (walls, ground, ceilling…) is one mesh.

For the settings, I set the lightmap resolution to 1024 and I have no error when I build the scene.
I put a LightmassImportanceVolume and a PostprocessVolume around the house and of course skylight, directional light…

My Lighting quality is in production mode and when I build the scene you can see some stranges shadow appearing in dark areas and corners.
Can you help me to fix that ?