ok, I found a work around untill this problem is fixed.
open the QtLockscreen.ini file with any texteditor, like Leafpad, and change the line where is says
"portrait" into "auto"
then as usual do a "killall qtscreenlock" within xterm and you're done!

By the way, it could still be a problem after you changed the ini file. just rotate your phone a couple times. After that, it should work!