Did you know that there are two types of Vault Cache ‘Reset’? As a reminder you can access these from the Enterprise Vault Outlook Add-in Diagnostics window (Control + Shift + click on an EV button in Outlook):
As you can see there are two types of reset:
Partial Reset -> Resets only the header. The next synchronisation will be a full header synch.
Reset -> Resets the header and the content. The next synchronisation will be both header and content; just like when a user was first configured to use Vault Cache.
Hope that helps!