I logged back in to amend my return, as I was issued a W-2c. I selected the appropriate reason for amending, and was directed to the "Here's the info for your amended federal return" page, where I was prompted with "Start" buttons to amend the necessary fields. When I clicked "Start" on the Wages & Income button, the page refreshed to show the grey "Edit" button had replaced "Start". When I click on "Edit", I am redirected to the very same page, instead of the form I need to edit.
Yes, the links don't always work as intended, but there's always another way to get to where you need to go.
Here's how to navigate to the W-2 page: