Remote/observed repos have a URI that Diffusion observes, and they can also have URI(s) for Phabricator users to use to clone the repo. In Diffusion, in a remote repo's Manage Repository → URIs settings, clicking a clone URI leads to a details page with a purple Disabled box, even if that clone URI actually works.
Version: the version available on https://secure.phabricator.com
Reproduction steps: see, for example, https://secure.phabricator.com/diffusion/CIRCLECI/uri/view/181/, and then (successfully) git clone the URI specified on that page. However, "Enable URI" is disabled because You can not manually disable builtin URIs. To hide a builtin URI, configure its "Display" behavior instead. (Well, that's what I get on my own install. On secure.phabricator.com, I get a different error because I'm not an admin.)