Web folder stuck on Loading, first-time use takes longer

Hi

I did setup ADFS for SSO to access Enterprise Vault.cloud. When I type the URL in the browser I get logged to my archive and SSo works fine. But when I create a Web folder on Outlook and set the home page to my archive it gets stucked on "Loading, first-time use takes longer". I can see the authentication process on my ADFS Event Log and it seems fine, the user gets logged on. But outlook keeps showing the message "Loading, first-time use takes longer"