I HAVE FOUND IT. It worked for me. I imported my USD objects into my content folder, then I selected the “root” of my usd_Stage, and duplicated it. Renamed it to be sure, and reloaded the level. Every root duplicated are still there. Don’t know if that a bugg. I can edit mesh, material and pretty much every-thing and keep ias it is when reload the level or restart UE5