In which board are you regularly posting? If it's Discussion I may have the answer.Also, I can tell you that from time to time the Administrators clean up old topics and delete them the forum.
Check this topic: https://cit.gg/index.php?topic=290055.0
If you reported a bug and it disappeared then it was either moved to topics for deletion (you can check if it's there from profile > show posts)
It's not shown in my posts, checked before.
Could be moved to a private board you have access to. For me you have 344 visible posts yet under your picture it says 345 which indicates it's on a board I can't see (this is probably why it's "gone")
Then it's in private board , bugs that are ready to be fixed are moved there so Arran and Brian can check them , only QAM have access to that board , so it was not deleted and you don't need to re-report.4
If your problem gets solved, let me know so I can lock this topic. @TJ