I found that some of my apps (that regularly emit notifications through the notification center, such as Dropbox or Cyberduck) dont appear in the notifications settings page.
For example, I use Cyberduck as FTP client. Every time I edit a file on my server i get the notification "File blahblah updated" and it also appears in the notification center on the right.
I want to disable the sound of those notifications (not the notifications themselves), but Cyberduck is not listed in my notifications settings.

I tried to reset my [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\PushNotifications] using this tutorial How To: Fix Missing Notifications in Windows 10 | Windows 10 content from SuperSite for Windows
and some new icons appeared (like Xbox or Outlook 2013), but not the one I needed.
I know that new apps should appear when the first notification is pushed, but that is not happening here.

I don't know what to do anymore. Can anyone help me to solve it?

Attached my notification settings. I'm sorry for the language but my windows 10 is in Italian, anyway you can get what it is.
Click image for larger version. 

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