I've noticed that when an issue is resolved on the last day of the month then such a query won't include them: resolved >= 2014-06-01 AND resolved <= 2014-06-30 AND assignee in ("name")
I thought that maybe my timezone and JIRA's is different but it isn't (it's the same; although in JIRA System settings as the time zone it says "Berlin (GMT+1)" however the time zone of Berlin is GMT+2 hours currently because of summer time): I resolved the affected issues on the 30th at 23:50 (as seen in the issue's history).
So is there a bug in JQL or is there a bug in JIRA not handing daylight saving time?