Cannot edit articles when SSO-HTTP plugin is enabled

[GJSchaller]

I recently migrated my Joomla site for our Intranet from a LAMP / Apache server, to a Windows / IIS server. This happened about the same time Joomla 3.5 came out, and we upgraded.

After the migration, I noticed an issue - users can no longer edit content from the front end of the website. It can be edited from the back end (where SSO is disabled), but when the "SSO - HTTP" plugin is enabled, users are no longer able to edit content - the page refreshes, but the editor never comes up, and no error message appears on the screen or in a log.