I have a mystery.  Gmail for Business.  El Capitan 10.11.3.  Outlook 14.6.0. 

I have a new identity and new user created. 

When re-synced the IMAP accounts, there were messages in my Starred folder with Reminder flags, but without the actual reminder date.  I was told by the forum moderator that I'd have to recreate the due dates, but I must not have done that properly. 

I assumed that the Reminder-flagged messages in the Starred folder could be set with a Due Date and Reminder Date, and moved to the appropriate folder for followup.  It now appears that the Starred folder may just be a label or reflection of the message status, as shown of another folder. 

When those messages in the Starred folder were set with a Reminder date and dragged to any of my named folders, the red Reminder flag showed up for a few minutes and then vanished.  But I didn't know that the reminder flag was being reset until days later when I didn't get the Reminder. 

It appears that the if I find the message in the actual folder and reset the Due Date and Reminder Date that the message stays flagged properly.  Can anyone confirm this? 

Is there anything else that I need to do, consider, etc.? 

Thanks!