You are correct, you do need to add that information in 2019 even though the sale was from a prior year.
I put an entry in to see how it is handled and It populated as required on form 6252. I suggest you go back through the installment income section and review the entry there to make sure everything is stated properly.
You may have to delete the entry and re-enter it as a last resort.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
