Hopefully this helps ..
Below is the main gallery screen with a filtered list.
I've captured the ITEMS command.
Gallery Items
The gallery item button is programmed to go to the Detail Screen
Gallery Navigate On Select
The details screen populates fine .. I've captured the DATASOURCE command.
Detail View Source
The EDIT PROJECT button is programmed as seen below
Note that I am using EditForm command, which should edit the Sharepoint list entry, not create a new one.
Detail View Navigate to Edit Form
The EditForm populates correctly with the fields.
Edit Form Data Source
Changes are made to the fields and the SAVE button command is shown below, which is SUBMITFORM.
Expectation is that the list item is modified, however, a new list item is being created.
Edit Form Submit Command
Thanks for any help that can be provided.