language and regional format set to english (united kingdom) but the panel clock switches to 12h (am/pm) after reboot.
What is the output of the following command:
gsettings get org.ayatana.indicator.datetime time-format
... and (after reboot):
locale | grep -i time
everything is set to locale-default (en_us in this case) even though i have set regional formats to en_gb in the language support application. looks like a nano session to fix this one as i cannot find anything in control centre to deal with it.
Although I don't know what's going on with your locale, you can switch your clock indicator to 24-hour mode (instead of locale-default).
gsettings set org.ayatana.indicator.datetime time-format '24-hour'
thanks it's sorted now though. changed LANG=en_US.UTF-8 to LANG=en_GB.UTF-8 in the terminal using nano. it looks like language support application found in system -> preferences -> personal is not working as it should with this release.