Well, you've already read my blog post, and I haven't seen anything since then that would change what I thought about it then, so I can't add much more. All of the evidence I have seen suggests that the Germans had essentially no knowledge of the Manhattan Project, though they suspected the allies must have a nuclear research program which they thought would be on par with their own (which is to say, no Manhattan Project). As for how they "missed it," it appears they just weren't looking for it, and they had very poor coordination between the Abwehr (foreign intelligence) and their scientists in any event. The Abwehr in general did not do a very impressive job against the United States. If they had looked for evidence of it, I do think they would have seen it. But you don't see what you don't look for. As for why they didn't look, again, they weren't coordinating well with the people who might have told them what to look for, and it also appears that the German scientists were so self-confident in their own superiority that they couldn't imagine the Americans out-doing them at this effort, so it never occurred to them to suggest that the Abwehr look for a larger project. (To put it another way, it is exactly the reverse of the allied situation, who were so afraid of the German program that they constantly sought out evidence for it, and tried to bomb and sabotage it at every turn, even though it turned out to be quite small. There was, as I sometimes put it, a "fear asymmetry" between the two powers, and that led the allies to do a lot of things the Germans did not do, including the Manhattan Project itself.)

But if you have any more specific questions I'd be happy to answer them.