I have Outlook 2013 set to sync with my Gmail via IMAP and to include 12 months worth of emails in local storage. This was working fine for the last few weeks and then something happened today and my inbox was emptied. I don't remember deleting anything, and all the messages are still in Gmail (in the Inbox, not the Trash or Archive folders either). I cannot for the life of me find a way to make Outlook re-download all the messages.
I have tried adding the All Mail folder in manually, but cannot get it to sync that one (always reverts to "Local folder only"). I have tried increasing the offline/local storage from 12 to 24 months. That downloaded everything up until exactly one year ago, but would not go past that.
The one thing I can think of that I haven't tried yet is to completely remove the account and re-add it. I would prefer not to do that if possible. Are there any settings in Outlook or Gmail that will reset the "downloaded" flag on all the messages so they will all download again?