I disagree with the other answer. I believe you can file an amended 2019 tax return to claim the Lifetime Learning credit (LLC) for the $6600 you paid "out of pocket" (you shoulda already claimed $1350 of that). The $5250 of tax free assistance has now been reclassified as a loan. As you surmised, the tuition has now been paid with your after tax money, not employer tax free assistance.
You cannot claim a repayment deduction or credit, for the $1350 because it is less than the $3000 minimum. But, if you failed to claim that 1350 for the LLC, you can do it as part of the amended 2019 return.
