EDIT : weridly, if go into the modelling tools > edit normals : the preview display the mesh correctly, without any holes… so I tried editing the normals and apply the changes… but as soon as I exit the modeling mode the issue comes back.
EDIT : weridly, if go into the modelling tools > edit normals : the preview display the mesh correctly, without any holes… so I tried editing the normals and apply the changes… but as soon as I exit the modeling mode the issue comes back.