Like @Saif mentioned we will have this checked with the product team. One point to mention though is that it generally takes around 15-20 seconds for the API to update any changes. So, if these tickets were modified immediately before you made the request then you might be getting certain stale values or you might not be getting some tickets. Could you confirm that this is happening even after a considerable amount of time has passed once the tickets were created/updated ?
So to be clear these two tickets were created and closed ~2 years ago as far as I can tell nobody is updating them so I believe it is safe to assume that I am making the request a considerable amount of time after they were updated/created.
I have tested this request multiple times and have had those two tickets within the response data every time.
We were finding out a way to connect with team to bring this to their notice. They confirmed it as a bug. We are actively working with them to involve in a process to track the bug fix.
We tried re-indexing our APIs to not let this happen. We waited for you confirmation if the issue has been solved for you. Assuming that it did, I would current mark this topic has closed.
If you need further help, Please feel free to create a newer topic to continue discussion and cross link this topic if helpful.