401k Excess Contribution rolled over into an IRA

My prior employer failed their 2023 compliance testing, but I rolled over that 401k w/ADP into my Vanguard IRA in January 2024. I received a 2024 1099-R for the excess contributions. I believe that I need to unwind this with Vanguard. However, Vanguard is requesting an earnings/loss statement from ADP in order to remove the excess portion. ADP, who issued me the 1099-R with the Distribution Code 8, is telling me they are unfamiliar with this request and it shouldn't be necessary in this instance.

Why would Vanguard need an earnings-loss statement from ADP? I'm already being taxed on the entire excess distribution. Wouldn't Vanguard just need to calculate the earnings-loss from the time of rollover? I'm not blaming this on either provider and it's most likely due to my lack of understanding.

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