Arf, maybe I should have re-read the bug report better. Depending on which settings you're referring to which are set to show times as 12-hour; you'll want to maybe set the time formats in evolution where I mentioned, or if it's already at "Use default for locale", for a locale which should display 12-hours (e.g. US English), set the format to use %I and let me know, since there may be an issue with locales definitions.
Arf, maybe I should have re-read the bug report better. Depending on which settings you're referring to which are set to show times as 12-hour; you'll want to maybe set the time formats in evolution where I mentioned, or if it's already at "Use default for locale", for a locale which should display 12-hours (e.g. US English), set the format to use %I and let me know, since there may be an issue with locales definitions.