Yeah, I get the same thing for importing ItsDed stuff into the 2021 Online software.
I suspect that all the modules in the 2021 software are not ready yet....there's tons of stuff in the 2021 software that isn't ready yet.
Try again in another week....but definitely not before the 6th of Jan.
Might not be even until after 20 Jan, when the Schedule A is supposed to be coming online.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*