Make a collection of combo box's selected values of form when opened in edit mode

I have a Power Apps SharePoint list form.

A SharePoint list choice populates a hidden multi-select combo box called DataCardValue4.

When the form is edited, I must collect the combo box's values.

SharePointIntegration Edit:

ForAll(DataCardValue4.SelectedItems, Collect(colVehiclesRequested,ThisRecord.Value));

This works when the user manually opens and edits the form.

Unfortunately, my Power Automate flow opens the form in edit mode.

When the form is opened in edit mode, DataCardValue4.SelectedItems is empty at the time of SharePointIntegration on edit.

What can I do?