I'm here to redirect you to the right support, @Rox1952.
Ideally, applications with an integrated connection can automatically download your transactions at a given time. Since you've got issues with missing transactions, some but not all on a monthly basis, it's best to contact the Technical Support Team of Square.
With their tools, one specialist can pull up your account information and determine why your transaction didn't sync as expected. Follow this link for the contact information: Connect Square with QuickBooks Online.
Need help performing any tasks related to your business account and company settings, click here to access and browse all articles for QuickBooks products. This reference contains most resources with steps on how to update your data and security management, to name a few.
Don't hesitate to post again here if you have other questions or concerns with QuickBooks application integration. I'm always around happy to help. Stay safe and have a good one!
