Over the last week, there has been a Microsoft security update released via Windows Update which is causing graphics on Microsoft Dynamics GP Report Writer reports to show as black boxes.
The Microsoft Dynamics GP support team is aware of the issue and is working to find a resolution. The current work around is to roll back the Windows Updates that caused the issue and pause updates to prevent them from being installed again.
[Edit] 20-Mar-2021: The Windows team have released a fix for this issue, it look’s like it needs to be installed manually. Please see the updates on both the articles from the Dynamics GP Support team and from Beat Bucher (links below).