In my opinion you should be eligible for stage 1, but there is some conflicting information on their website: https://www.federalregister.gov/documents/2025/07/10/2025-12803/supp...
"SDRP Stage 1 provides a streamlined application process for eligible crop, tree, and vine losses during the 2023, 2024, and 2025 crop years due to qualifying disaster events in the 2023 and 2024 calendar years for which a producer:

Received an indemnity under a Federal Crop Insurance policy that provided coverage for a loss of crop production, revenue, or quality, or a loss of trees or vines, excluding policies for forage seeding, policies for crops with an intended use of grazing, livestock policies, Controlled Environment policies, Margin Protection Plan policies, banana plants insured under the Hawaii Tropical Trees provisions, supplemental policy endorsements based on county- or area-level losses when purchased with a base policy, Cottonseed Endorsements; and policies issued in Puerto Rico"

Based on that it seems like you are not eligible, but the next paragraph says this:
"Payments based on area- or county-level insurance policies will only be included in Stage 1 when they are the producer's base policy, because excluding those policies would prevent FSA from using Stage 1's streamlined approach for those insured crop losses that would otherwise have been eligible."

I would say that the issue is that because your individual yields were not reported through RMA because you carried MPP the FSA does not have a pre-filled application with your name on it.