I agree, there should have been no code L1 2019 Form 1099-R since the loan was satisfied by the 2018 offset distribution reported on the code M1 2018 Form 1099-R and you had no loan in 2019 on which you could have defaulted in 2019. You need to obtain a corrected code L1 2019 Form 1099-R from the payer showing $0 distributed.
