The same thing is happening to me. I used to get a ton of impressions from Story/Idea Pins, and a lot more traffic to my blog from my static Pins, but that has all dropped tremendously. I post fresh content, I space it out, and still nothing. My limited follower growth has also dropped as a result.
I don't really get it. I follow all the best practices, and can't get seen. I've reached out to Pinterest and received no response.