I am having the same problem in Turbotax Business 2021 when transferring a 2020 return. There are two 50% partners and neither one is in the new 2021 return. This occurs on only one out of a dozen returns. That is, 11 returns are transferred from 2020 to 2021 correctly, but one is not.
Turbotax developers: I can give you the 2020 return that is not transferring correctly. You should be able to step through the transfer and see where the failure is occurring.
