Please try to manually update your software instead. Refer to the following Help Article for instructions: Manually Update TurboTax for Windows Software (Basic, Deluxe, Premier, Home & Business)
I have the same problem. The article linked has no instructions for manually updating TurboTax Business 2020. I've uninstalled TurboTax Business 2020 and reinstalled and updated and it still says form 8960 is not ready.