Folders not appearing in the Sync select list

Hello community,

On my NC instance, I have Group folders.
One user told me He can’t see some folders created by an other user in the same group.
I have check on the web interface with the user and the folders are visible.

I have check on the desktop client (W10) and these folders not appearing on the client, they cannot be selected because there are not visible.

What can i do for this problem ? (Because i don’t have any idea)

Thank you a lot !

Nobody having this type of issue ?
I mean, it’s not a easy issue, but my users use a lot the client and i have to tell them to use the web app …