Vbills may only be edited when they are in a 'Work in Progress' status. Once they are submitted online by the vendor, they leave this status and are in 'Pending' until acted upon by Accounts Payable personnel.
A Vbill that is in a 'Pending' status (indicated by the radio button selected next to 'Pending') will not be editable. This is by design.
If you wish to make modifications after a Vbill has been submitted, you will need to contact firstname.lastname@example.org and request that the Vbill be returned to 'Work in Progress'. Include the reason and your Vbill ID.