January 2025 here, found this article because I'm having the same issue. Was missing 12 of 15 transactions from September 2024, including the tax payment I made in QBO itself. Downloaded all of my 2024 transactions from the bank and compared to all 2024 transactions in QBO. 45 additional transactions are missing. Astounding that the biggest and most universal accounting software can't get something this basic right even for a simple self-employed person.