Hi there, Liulin. We're aware of the issue regarding creating billing in QuickBooks. Our engineering team is working to restore the functionalities to normal.
We appreciate your patience as we work to fix this as soon as possible. For you to receive updates, I suggest contacting our Live Support for further assistance. Please refer to this article for details, along with our operating hours: Get help with QuickBooks products and services.
Post a reply below if you have other QuickBooks-related questions.