Exchange 2010\Outlook Mail issues

Hi,

I am having some issues with mail disappearing and outlook not updating. The issues are:

• When sending an email from Outlook it appears in the sent items for 30 seconds in Outlook and then disappears. It never shows up in OWA The email does send though. If an email is sent via OWA the email appears and stays in both OWA and Outlook. This is happening in Outlook 2010\Exchange 2010
• Updating issues on random folders in Outlook. This is happening on both Outlook 2013 and Outlook 2010 different users with the same Exchange 2010 back end. 

Both users have cached email forced. I have tried rebuilding the mailbox locally.

Cheers,

Zac Avramides