Steps to recreate:
1. Comment on a suggestion. Note comment count is 1.
2. Disable comments for that product.
3. Enable comments for that product. Note that comment count for suggestion with comment on it is zero, even though you can see the comment.
4. Adding a second comment doesn't increase the comment count from zero.
Edit: I may be confusing the product by being the admin and a "user" on the same machine using the same browser (Chrome). I am using an Incognito session to view and submit suggestions, vote and comment. However, I can still see the "unmoderated" comments. When I approve these comments as the admin (in a non-Incognito session), the comment count appears as correct.