I have 4 websites that were hit with a google penalty in august. I will pay big money to someone if they can resolve this issue.
I checked and there are too many keywords if not all that point to your site with the same keywords. That really looks not natural. Try to add some human/natural words/phrases: Example: "how to {your keywords}" "You could learn more about {your keywords}" and so on. I believe its applied to the G latest algorithm. I have same experienced as yours. I think you get the picture, right?
They now added semantic algorithm (more human thinking/words), so the links that point to your sites should be describe why they want to point to your sites. If there are just keyword, it will not make sense to G nowadays, and even G thinks its automation works. And automation means allow G spam team to give it penalty.