I have been using Scriv3, in their quasi-public-beta program, for many, many months now – actually wrote my forthcoming book entirely using this 3rd release. Just purchased the formal release version today.
It’s a great evolutionary step up from the previous also-exemplary versions of the program, but you’re right that it’s not fully matched with TB at the moment. My experience is like what you report: hierarchical structure and note names are correctly transferred, but not the text of the individual notes. I assume this is just a matter of Eastgate learning about the new coding protocols and adjusting accordingly.