APM Linux client doesn't seem to work

OK, trying to connect with a linux client - fedora 20 workstation. Using firefox, have installed the plug-in.

After putting in credentials it goes to

Checking client...

then

Collecting machine info...

then fails. The log shows no session.client.??? variables and gives no error, just

\N: Session deleted due to user logout request.

the same configuration works for iOS, android, windows & mac

any ideas?