An earlier attempt at submitting these files failed.
I re-uploaded the failed files (indicated in my previous notebook entry linked above) and tried again.
It failed again, despite having successfully uploaded just minutes before.
I re-uploaded that “missing” file and tried again.
This time, it succeeded (and no end-of-stream error for the 1SN_1A file!)!
Will post here with the SRA accession number once it goes live!