Nothing shared but "Shared with others" shows something

I’m trying to restart sharing from the beginning since it does not work properly with my colleagues (come can sync everthing, other don’t receive some files, file acess control doesn’t work), so I’m removing all sharings. Even though no folder / file is shared, one folder is displayed when I click “Shared with others” on the web interface. Is the folder internally shared or nor ?

Thanks,

Gilles