In your first photos, it's clear that some of your seeds sprouted and the rootlets died, as well as some showing nubs sprouting but dying before rootlets could form, so some of your seeds are or at least were, viable at that time. When a living organism dies, it begins to decompose (rot). I think the green/brown color on some seed parts are showing that rot. Mold is a condition I think we have all encountered and if viable seeds are isolated from the moldy ones before they are contaminated, they should go on to sprout.
