Hi Doug,
To further troubleshoot the issue, I’d like to confirm the following tips with you:
- Are the Windows user encounter the same issue?
- Have you tried to update the Lync’s version to the newest in Mac and try again?
- Have you performed a clean startup (safe mode) to determine if there is any background program are interfering with Office for Mac?
- Is there any service upgrade carrying on or performed for your subscription?
- Also, for test purpose, could you please try uninstall Lync and Office clients on one Mac, then reinstall them to see if the same issue persists?
For more details, please refer to: