I spoke about this before.
You go to Options, Account and then you click or press Synchronize command, which will synchronize your profile to the test server.
Upon synchronization, a 24 hour cooldown will be given and you’re unable to re-synchronize during that period!
You’re also unable to synchronize, when the test server is OFFLINE.
Problem is, that I tried with another synchronization after the cooldown period and when status of the test server was set to ONLINE.
I was unable to synchronize, because the command was greyed-out/unavailable. I also got [error] message shown!
Notice: This issue is not only related to me. I got other people having the exact same problem, like stuck synchronization message, even after the cooldown period expired.
Request: I request, that you enable the test server again, just to see, if the error message will disappear or not. The problem is, that when the server was online, it didn’t, but that was a patch or two ago.