@psilly0
This is not a bug. Since 2016 or so, it has been required that you can only e-file a state return if you also e-file a federal return at the same time. This is a security procedure to prevent e-filing of fraudulent state returns.
In your situation, where it is necessary to file separate federal returns and a joint state return, you must prepare 3 Turbotax files. One of those files is a joint federal plus state return, where you discard or ignore the joint federal return and file the joint state return. For the security reason described, that joint state return can't be e-filed.
