For ubuntu user's on 18.04. to fill the password field you need to set keyboard input to Xim instead of lbus and restart your computer. this can be done in language support as last setting. This seems to be a bug in ubuntu it self as it is a problem on multiple addons.

I changed back to lbus after login as that's default.

Maybe this can be added to the support page? So the next person don't need to google and read the bug reports