one reason might be because of daylight saving: DaylightSavingsTimeIssues
Also did you check the jboss log to find out which timezone it is using? like -Duser.timezone=xxx", where 'xxx' is your timezone name
but figured it could be the summer time but was not sure, I'm using parameter -Duser.timezone = xxx in my standalone.conf, and still did not change the schedule.
Thank you for the support!