Windows Server 2016 - Search Indexing Issue

Hi to all 

sorry for my bad english 🙂

I've this issue with Windows 2016 Search Indexing Service.

So this is my scenario:

i've selected only 1 folder (Extra Start Menu) for search indexing : this folder is a specific folder "F:\FileServer\Documenti Aziendali". 

Well, at this point indexing service start to index the folder, and the search from both SMB and direct Windows Explorer (of the server) it works fine.

At some undefined point (1 Hour or 2 days later or ? ), the searches return white file icon results (these are not clickable ). (Attachment_1.png) both direct server and SMB.

If i open the Search Indexing GUI, the folders are gone! (Attachment_2.png)

I can temporarily fix the problem by restarting the service or rebuilding the index (Attachment_3.png)

As long as the service returns the indexed folders, everything works. Conversely I get white file icon results

EDIT: No Error or Significant Event in EventViewer 😞 

How i can resolve?

Thank you for support 🙂

Federico