It wasnt Wine I don't think.
Was the error message I was getting.
Which was fixed by, "it worked for me when I double clicked a realm, rather than using the button at the bottom" suggestion.
Might work for you too?
I think the bug fix has gone through though yea. Unless the wine issue is different, as it wasnt letting people log in at all I read. Maybe I slept through the wine issue, but when I got up, i could log into some realms fine, but when switching i got the above topic error.
So dunno... possibly though it was not a wine issue, but just a patch glitch :).
They had the servers down for a hot fix today i believe :).
Hope its working for u now man :).
Edit: Weird though, Wine runs it fine, Crossover runs it fine [for me] but PlayonLinux is getting the stuck at Sign-in screen... weird :-O...