Silent failure on iOS only ?
It seem that the connection don't work everytime on iOS for me either, but i have an auto-retry function the inhibate the previous connection call if it timed out.
Can you do this dumb test in your code, call CreateJoinRoom twice, and see if the second call fire a Success or Error delegate.
If you can workaround this way, i highly suggest you to code an Helper function that does this retry attempt automatically.