Yes, it's a bug; I've agreed with you on that from the beginning.
It has nothing to do with which Windows operating system is being used. The bug manifests when the current version of 2019 TurboTax, R9, is run in Windows 7 on your machine and in Windows 8.1 and Windows 10 on my machines. I have to believe that any TurboTax rep that can't reproduce the bug is not testing for it properly.
This bug was introduced with 2019 TurboTax update R8 released on 12/11/2019.
