Hi @Davide Lodi ,
Welcome to our forum!
What's your account? An Outlook.com account or something else?
And what do you mean about "raw format"?
As i know, when some or all items disappear from a given folder in Microsoft Outlook, this issue occurs if a filter was applied to the default view settings of the Outlook folder. Please refer to this article and check the view settings:
Items disappear or are not visible in an Outlook folder
Hope to help you!
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