#17 - July 30, 2014, 8:58 p.m.
Yep! If you're seeing realms as incompatible, your client likely hasn't picked up the update. Restarting the Battle.net App can help it recognize that there's an update available if it hasn't found it automatically.
As to the update itself, it's just a tiny bugfix patch to allow Garrisons to be upgraded, not a full build.