Hello,
At this time, I am unable to find any Microsoft incident, service advisory, or official documentation confirming a known issue where arrows or stepped connectors disappear from Microsoft Whiteboard. However, I have found reports from other users indicating that the Whiteboard interface has recently changed, including the toolbar moving from the bottom of the canvas to the left side, which could be a recent product update rather than a local issue.
Given this, I would strongly recommend reporting the issue directly through the Microsoft 365 Admin Center so that it can be reviewed by the Microsoft Whiteboard engineering team. An administrator can submit the report by navigating to:
Microsoft 365 Admin Center > Health > Service health > Report an issue
If you are not a Microsoft 365 administrator, please contact your organization's administrator and ask them to submit the report on your behalf.
In addition, I encourage you to submit feedback through the Microsoft Feedback Portal. The Microsoft product teams actively review customer feedback, and many product improvements and fixes are driven by feedback received from customers.
The more reports Microsoft receives from affected users and organizations, the greater the visibility of the issue. This helps the engineering team investigate the behavior, determine whether it is a product defect or an intentional design change, and take appropriate action if necessary.
Please feel free to let me know if you have any further concerns.