Upon cloning and selecting the "All Columns" upon exporting people from Marketo the Lead ID column is missing from the export.
It is expected that the Lead ID is not included in the export even if the "All Columns" is select upon exporting, the reason for this is because the Lead ID is unique to Marketo as Email address is used for identification purposes outside the platform.
The Lead ID will only be included in the export if this is added to the current view of the list, if this field is missing from the view you can navigate to the list > select "View: Default" > "Edit Default" > in the Hidden columns search for the field "ID" and just hit the add button to move this field to the "Visible Columns".
After the view has been edited to include this column users should be able to select the export option now. Upon selecting export, now instead of selecting the "All Columns" the user will need to select the option "Visible Columns" now and this will allow the Lead ID to be exported.