I'm having the same problem with all browsers.
I just upgraded to the latest Elastix version (2.2.20?) and couldn't connect to Fop 2.23.
I upgraded to 2.24 and restarted the fop2 service. I also cleared the cache on all browsers (IE, Chrome and FF).
On Chrome it tries 15 attempts and says System Unavailable.
IE and FireFox both stay at Attempt 1 and never progress.
This was a pre-existing install of FOP2 so I'm not using the new FOP2 installation from the add-ons page (although, is it possible to get FOP2 re-integrated with the add-ons page?)
I think we fixed your problem via the live help. FOP1 was re-enabled when upgrading Elastix, disabling FOP1 fixed the issue.
