Minnesota Life/Securian review: Car loan disability insurance

I have two cars; both have Securian disability loan insurance. In May of this year I had a seizure and had to take two months unpaid medical leave from work. I filed a claim with Securian for the missed car payments. Last week (three months later) I received a separate decision for each car. Securian will cover missed payments on the Dodge. But they denied the claim for my Nissan because, they say, my doctor indicated there was a pre-existing condition. If I want to challenge it, I need to have my doctor send a statement saying there was no pre-existing condition, and also submit my medical records back to October, 2021. My doctor told me she did not indicate a pre-existing condition because there was no pre-existing condition. I never had a seizure before that. I have no condition that causes seizures.

It seems the two decisions are mutually exclusive; how can I have a pre-existing condition that only applies to one car? Should I send them the statement and/or paperwork? Or should I be happy that I got anything at all?