https://support.microsoft.com/en-us/help/4049314/microsoft-dynamics-365-for-outlook-is-unable-to-render-webpages-after
In short, a security update for Outlook makes the Outlook app for Dynamics 365 unable to load data and to resolve this you need to add a registry D-word on the machine that runs Outlook.
It's a bit unlucky that there are clashes between different program's updates but a security update is seldom a bad thing so it's good that there's a work around for it.
Rickard Norström
Developer at CRM-Konsulterna
www.crmkonsulterna.se
Developer at CRM-Konsulterna
www.crmkonsulterna.se