I had the same problem and finally found out that it was a problem of different locale settings in kde and basic settings.
While I had changed the number format in KDE to use decimal points, the locale number format LC_NUMBER was still "de_DE.UTF-8. Adding the line
I had the same problem and finally found out that it was a problem of different locale settings in kde and basic settings.
While I had changed the number format in KDE to use decimal points, the locale number format LC_NUMBER was still "de_DE.UTF-8. Adding the line
LC_NUMERIC= "en_US. UTF-8"
to /etc/default/locale fixed the problem.