I experienced the not at all working updater as well.
Coincidentally i found out that only data is downloaded and the gui updated shortly after the window was made visible again, as brought back in the foreground or i switched back to the workspace the updater ran on from another workspace. It also helped to move another window over the updater and close the window there.
As i am an extremly lazy person and i am using gnome i opened a gnome-terminal an executed the following command (without leading and following quotation marks):
"for i in /dev/; do for i in /dev/; do gnome-terminal -e exit; sleep 1; done; done;"
This will open a gnome-terminal automaticaly every second and automaticaly close it again. If you now make sure the gnome-terminal appears above the updater window the updater will update his gui and keep downloading and therefor updateing. Also this is a very ugly workaround it worked like a charm for me.

Hope this helps anyone...