Shared subfolder missing - how to get back?


GW2014R2 - 14.2.2- latest Client

one user has shared a big folder structure including several subfolders,
so far so good.

Now one receiver of this folder structure is missing one (!) subfolder,
maybe deleted by accident...

To make this clear, the folder is there and in the other receivers
mailboxes it's visible.

Now the owner can drag this folder out of the structure, and drag it
then back into it. But this may be confusing for the other users.

Repair all Sub-folders in the client doesn't help.
Is there any other way to restore this shared subfolder for one mailbox?
gwcheck option or something?