By default Appointment Reminder doesn't sync All Day events from Google Calendar. If you want to enable All Day events then you will need to enable this for each Google Calendar.
Go to Settings > Edit Calendars and click edit on the Google Calendar you want to edit.
Scroll down to to the Google Calendar options and change "Sync All Day Events" to true.
Once done you will need to run a full sync on your Google Calendar to update and add any new appointments we previously didn't sync.