why my shared file deleted by itself?

Question

I have one server and 24 clients in my company. There are shared office files when new clients(3 clients introduced) change in a set of office, especially excel and word, and save my shared office files.

My share office files are hidden and if my new client is the administrator can see the shared office files but can not open and encounter access denied error and can not be copied or anything. If the new client wasn't administor can not see it
I do not have this problem if I share photo files or other items.
Office files that are not shared and they are on their computers new clients change them they do not have this problem.
All permissions and settings in the active directory are correct and other old clients have no problem. Only new customers have this problem.