It happened again and I think I know what caused it.  I deleted a comment in a conversation and the negative value showed up.  To test, I went to another conversation and made a new comment.  I then deleted that new comment, and a negative value showed up.

Hello. Unfortunately I cannot reproduce on fresh installed ci.una.io demo site. I did the following:
1. User1 created a Discussion. He will receive notifications and watch for counters.
2. User2 posts a comment -> User1 got (1) in notifications counter.
3. User2 removes the comment -> counter disappeared on User1 side. There is no Zero value here.
4. User2 posts 2 comments -> User1 got (2) and viewed the notifications to hide counter -> User2 posts one more comment -> User1 got (1) -> User2 removed 2 comments one by one between 2 nearest Live Updates on User1 side -> counter disappeared on User1 side. There is no Zero and Negative values here again.

Hi, it's not the discussion module, it's the conversation module.