Hi d_m18,
To further troubleshoot the issue, please confirm the following information
1. If you set your account in another computer, does the issue persist?
2. Do other users in your organization have the same problem?
Check the user’s status ,if the status is do not disturb,you will not get a conversation notification.
You could perform a clean boot in windows, This helps eliminate software conflicts in your pc.
https://support.microsoft.com/en-us/help/929135/how-to-perform-a-clean-boot-in-windows
Please update the client to the lastest version.
If the issue is still exist,you could install skype for business 2016 client or re-install lync 2013 and make a test.
Best Regards,
Leon-Lu
TechNet Community Support
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