After I upgraded to the Qlik Sense June 2017 release, I found that my "License Monitor" and "Operations Monitor" Apps no longer reloaded. There are 8 new Data Connections that need to have their Connection string values updated---for those of us who have customized the server listen port on the default proxy. All of these new Data Connection names start with "monitor_apps_REST_".
Once I updated them in the same manner that the "qrs_" data connections were, they successfully migrated, and are now working.
Once you are in Form Authentication, everything will be prompt for username and password. This somehow caused the operation monitor to fail (at least I think it is). So to avoid this, we retain the Windows authentication and create a new Virtual Proxy with Form authentications and it works for us. Hope this helps.