This issue has now been resolved. You can now transfer your 2018 TTD to your 2019 TTO.
*Due to technical issues, this feature is currently unavailable, as of January 17, 2020. Please continue to check back for further updates*
We have a great FAQ about transferring your 2018 return from TTD into your 2019 TTO- This will help you once the technical issues have been resolved.
https://turbotax.community.intuit.ca/community/importing-transfering/help/in-turbotax-online-how-do-...
