The workaround does work, you probably just forgot to set it in the individual conversion dialog. See for example:
https://bugs.launchpad.net/calibre/+bug/1001599
Or
https://www.mobileread.com/forums/sho...d.php?t=177741
Or
https://www.mobileread.com/forums/sho...04&postcount=5
Or a few others. Apparently, google doesn't like you