Benjamin,
I added the subscription to the account above as well, so now you can post from either and we won't pester you about your subscription
As for your issue, it looks like a caching issue, but a little different than we've ever seen before (mainly where the user looks logged in on that page forever). Can you try the following and let us know how things go after each step.
1) Disable all caching - in Global Config and the System - Cache plugin. This should fix everything
2) Re-enable the Global Config Caching on "Conservative" setting. Things should still work
3) If caching was on "Progressive" before, feel free to then try this setting. We haven't done a ton of testing with this setting, but in general, it should work without problems with JFBConnect.
4) Finally, to re-enable the System - Cache plugin, you'll need to make sure that it's ordered after (higher number) than the JFBCSystem plugin. Once that's done, re-enable it and test everything again.
Hopefully that gets you going. If you don't have caching enabled, are using a 3rd party caching extension, or none of the above helps, just let us know!
Thanks,
Alex