Could you provide us a screenshot if possible?
Does anyone else have the same issue?
It recommends you clear the client cache and have a try.
- Right click the Windows icon and open the Run bar
- Type in: %localappdata%\Microsoft\Office\1x.0\Lync\ folder
- Delete the sip profile folder.
- Go into the Tracing folder, delete all files.
If all users have the same issue, you could go to Lync server event viewer to check if there is any related error message in Skype for Business front end server.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.