Dear Jennifer,
It seems that I can't reproduce the issue with the same version number of the Word application as you.
About the issue could you upload some screenshots showing the issue for our reference?
Note: Remove any private information before uploading the screenshots.
Could you confirm whether you have your track changes settings set to use balloons for comments?

Meanwhile, some users may solve the issue by going to File>Options>General>checking if the "Enable modern comments" option is checked. If yes, clear the check box to see and let us know the result.
As you mentioned that the issue occurs with some comments. could you check whether you can reproduce the issue when you create a new documents with some new comments?
Welcome to share nay updates at your convenience.
Thank you for your time and effort.
Sincerely
Cliff | Microsoft Community Moderator