I wonder if the surge in hispanic voting, Latino Decisions thinks 2 million more latinos will vote this election, is causing people to confuse it with a decrease in black turnout.
For instance, and these numbers are being made up and not accurate by me, if last election it was 70% white non-hispanic, 15% black, 10% hispanic, 5% other and this year it's 67% white, 13% black, 13% hispanic, 7% other, this doesn't mean AA vote is down. It just means they make up a smaller portion of the electorate because more non-white (not hispanic) and non-black people are voting too.
Where we see the AA vote share going down we also see the white share going up.