NLA authentication won't work when kwallet support is disabled. Unchecking the "Remember passwords" in the main preferences and the per host preferences and I'm unable to connected to server 2012 machines or machines with NLA auth only enabled. I would think it would just always prompt for username and password or allow for remembering the username via "advanced options" or some other mechanism, but not the password. side note: disable "Remember passwords" in the main preferences doesn't seem to make the per hosts screen not have the checkbox to remember password de-selected by default.
*** This bug has been marked as a duplicate of bug 322361 ***