We have a small DAG with 3 member servers and one witness servers. Some time ago our forms-based authentication stopped working and we had to move back to basic authentication to allow for OWA to work. This works fine, but we would like to get the "pretty login page" back online.
We had a case open with Microsoft, requesting numerous traces/logs but so far we had no luck figuring out the issue. We have been trying different IIS settings as well. The only thing that was done at some point before the issue started was new certificates were applied to our servers.
We did also apply a CU7, which I assume re-installs the whole Exchange pretty much, but it did not clear the issue.
What we are seeing while the forms-based authentication enabled is the inability to log in. Putting the credentials in and hitting the Enter key re-loads the page and we are back to the login screen. Putting incorrect credentials works - the error stating that username/password is incorrect is properly generated.