clock scan with gmt fails to return the proper day until
your time zone changes to the next day.
I am in CST and if I run a [clock scan "1600Z" ] or [clock
scan "1600Z" -gmt true] or [clock scan "1600" -gmt
true] during the actual time frame of 00:00Z to 05:59Z,
it will return the previous day. It appears that the day
elements is not getting altered based on the GMT time
but by your own time zone instead. Included is a test
file that was run on the hour for several hours that
shows the problem.