Top right seems to have grown a new but inconspicuous combobox "For sale in:" with the default text "Choose a model to edit" where one can then pick the model. Not sure how or why this change is necessary to save the world now ?
Looks like it, but I wonder if it is really intentional - betatesting on a live system on a friday evening does not make sense, and others have reported missing models.
Apparently you need to drill down further from that pull down box to further edit the model and find the materials, details, and history information. But once you're in there the Details and Selling tabs disappear and you need to back page to get back to the original edit page. I'm sure it all somehow makes sense if you have a model set up for variants.