The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
Hello, I have same issue regularly (and currently)
"java.util.concurrent.TimeoutException: Did not observe any item or terminal signal within 60000ms in 'flatMap' (and no fallback has been configured)"
So... not sure what I can do... juse wait?