"allowOpenFromUnmanagedToManaged" -While Adding Photo to Managed App or Account

Am using a Supervised Device with 15.4 OS

Scenario: I have tried to push the Restriction payload to Device , with value true for "allowOpenFromUnmanagedToManaged" key .

case 1: When i try to open a photo from Photo Library and try to open in with any Managed App ,the suggestions for managed app is not listed there. (Working as Expected)

My Problem is: case 2: But when i open the Managed App and Try to add a photo , It allows me to open the Photo Library ,from where i can add it. If Sharing data from unmanaged to managed app is restricted, then it shouldn't be added in case2 ,Right?

FYI: The managed App i have used in Outlook App

Can Anyone Help me this strange Behaviour? Thanks In Advance