Your daily quest activity resets at 5:00 AM your local time, and Guild activity resets at 2:00 AM UTC.
If your local time zone is different from UTC, all activity and titanite earned between 2 AM UTC and 5 AM of your local time zone will not be counted in today's Guild activity. It is counted towards the Guild activities of the previous day.
To avoid this, you should not collect activity or titanite and upgrade Glyphs during this time period.