Sometimes Office does not render completely, and large sections of the screen appear blacked out as shown below. This is especially apparent when using external monitors, especially higher resolution monitors with docking stations, where there are many pixels to be rendered.
Microsoft is addressing the issue in subsequent updates to Office 32-bit. For more information see the article here, https://techcommunity.microsoft.com/t5/Outlook-Blog/32-bit-Outlook-will-soon-be-Large-Address-Aware/ba-p/105771 . Note, another article here explains that this may cause COM Add-In issues, see https://support.office.com/en-us/article/large-address-aware-in-outlook-2016-ea0913e4-2917-4456-b0ea-935dbd57ef02 .