Featured Image Capability Lost in 4.01

For existing posts and pages, I am no longer able to either, 1) remove a featured image, or 2)change a featured image.
Running a Genesis Framework theme. Apparently I can add a featured image to a new page/post, but when for an existing page/post. When I click on the Featured Image link for an existing page/post, it brings up the add media files interface, not the media library. When I select media library, the images are listed but not selectable.