I don't know why the plan admin won't change the 1099-R.
Perhaps you want to try them again explaining that you can't use the 8915-E with a code 1L.
I have had several experiences where "experts" tell me things that aren't true and a second call gets me to someone who actually does know.
I suppose you could enter code 1 in TT or paper file your taxes with an 8915-E but if the IRS sees anything with code 1L, they will want to know why you used 8915-E.
It's explainable but in reality, the plan admin should issue a new 1099-R.
