Gazza M -- Christian conservative views are still very embedded in African American voters. This can have a negative impact when progressives are overly focused on LGBT rights, and also work against them if they challenge family structure too much.
Your reference of under performance is spot on though. Ahead of 2020 Democratic President nomination, for Black Voters, Biden had a 69 percent share (nice....) vs Bernie at 20...compared to 44 for Biden and 36 for Sanders among White or 48 and 38 for Hispanics.
Another unfortunate consideration is that African Americans under index on attending college. There's strong correlation between secondary education and voting for liberal/progressive candidates.
But ultimately, my biggest takeaway when evaluating voting blocks is its lazy to look at them in singular groupings. Really we should be asking why progressives perform weakly for male African Americans? or female African Americans (I don't believe they do)? or young African Americans? or old African Americans? etc.
