I have been testing the Win10 beta side-by-side with my Windows Desktop version of 1Password (v4.6.0598) and in doing so I've found a number of items that don't have full data in the Win10 Beta.
Here are a few examples:
I have around 200 items like this (of my around 600 items), some of which are shown with a warning icon in Win10 Beta and state that they are an unknown Item Type (although not all do).
If I try and edit any of these items they don't have any fields, the 'editor surface' in the app is just blank.
I'm still using an Agile Keychain vault type with the app (if that makes any difference).
1Password Version: 2016.1.1200
Extension Version: Not Provided
OS Version: Windows 10
Sync Type: Dropbox, OneDrive