Source of Supply Not Automatically Determined in Fiori App

[LXBEL]

Hello,

I am experiencing an issue with the Fiori app "My Purchase Requisitions – New" (App ID: F1639A) 

When creating a purchase requisition using this app, the system does not automatically determine the source of supply in the Source of Supply tab.

However, for the same material, plant, and purchasing organization, the source of supply is automatically determined when using the ME51N transaction in the SAP GUI without issue

I reviewed SAP Note 3539290, which seems relevant, but unfortunately, it cannot be implemented in our current system version.

Do you have any suggestions? Thank you in advance