Can I still claim the MCC (Mortgage Interest Credit - Form 8396) if we sold our house and didn't live in the house for the entire 2021 year?

[Critter-3]

Yes you can IF they send you the proper forms for your taxes. 

[DaveF1006]

According to FDIC guidelines, the MCC tax credit remains in place for the life of the mortgage, so long as the residence remains the borrower's principal residence. In your case however, since you no longer own the house and pay the mortgage in 2021, you are not eligible for the credit.

[Mike9241]

from 8396 instructions

Who Can Claim the Credit
You can claim the credit only if you were issued a qualified
Mortgage Credit Certificate (MCC) by a state or local governmental
unit or agency under a qualified mortgage credit certificate
program.
The home to which the certificate relates must be your main
home and must also be located in the jurisdiction of the
governmental unit that issued the certificate.