I don't know if this will be helpful to you but I just solved a similar problem. I had just one transaction in my .CSV that was showing up once imported in QB as 01/01/1970 (should be 18/05/2024). I copied the specific transaction into a .TXT file, with the same formatting as the .CSV, and imported that just like the .CSV. It then showed the correct date in QB. I hope this helps.