I don't know if anybody else has had this issue, but I had managed to get all the hard-mode completion marks except for Greed/Greedier mode which I wanted to do last. I had not looked on the forums for help as I've been playing Isaac for a while and have a good grasp of the mechanics, so you can imagine my surprise when I beat Greedier mode (assuming I only had to do that much like every other Hard mode) only to not unlock ANYTHING even after having all the other marks.
Apparently, it's been well documented that you have to beat both Greed and Greedier mode, but what was not clear is that you need to beat Greed mode FIRST. My first successful Greedier run counted towards my win streak, but nothing else :( I had to beat Greedier again for a second time after Greed mode in order to get the unlocks. Hopefully this little tidbit helps somebody and saves them the minor shock.
Also, one other tip which I don't see mentioned too often but can be a difference maker. Make sure, if you have the extra bombs in Greed/Greedier mode to bomb the shopkeepers. They drop Steam Sales often enough to make it worthwhile and a few times I have gotten 2 Steam Sales in one run which basically guarantees a win as everything in the shop becomes free. It's how I got the last Greedier win and it made for a hell of a satisfying victory after what I went through before!