Yeah, I can't seem to reproduce that. Was it right after you logged in?
My only theory is that the initial post feed came in unauthenticated (which wouldn't have any blocks), you logged in, and then the main feed was still cached from the initial load.
Try just refreshing the page to refresh the feed and/or opening it in another tab. I'm currently waiting on approval to setup an account on lemmy.ca to see if I can reproduce it there. I tested on 0.19.7 and below, and the blocking all works as expected.
I tried this frontend and liked it, but the next time I went there I just got that spinning hypercube animation endlessly, with no other UI to interact with. Is there a forum to discuss that frontend or something?