Outlook calendar shared not updating
If there are a lot of folders, you can hit the limit very quickly and the mailbox will stop updating.
If you turn off cached mode for the additional mailboxes, then you don't have this issue.
I've never added a true Exchange Online shared mailbox as an additional account in Outlook, but this guy says it works just fine, including comments from 5 days ago indicating it's working: Bumping this thread because this just started happening with my Outlook 365 client.
I tried removing and re-adding the shared mailboxes but they still do not update - last emails received were 10th July.
There's also some general performance limitations with cached mode ( 100k items in a single folder) that could come into play.
This goes into more details:https://support.microsoft.com/en-us/kb/2768656https://support.microsoft.com/en-us/kb/3115602 run into this issue with one customer for a long time.
The most common reason meeting invites are not populating in your Outlook calendars is a problematic Internet connection.Without access to the Internet, Outlook won't be able to download meeting data from an Exchange or IMAP account.Once you've verified that your Internet connection is functioning properly, check that your account settings are properly configured.Without it, you may miss important meetings and other business appointments.A number of issues may lead to your Outlook calendars not populating meeting invitations.