Not working how? Posts that are blacklisted on Danbooru aren't blacklisted on Safebooru? Did you change your blacklists recently? If so, is it just the new blacklists that aren't working, or do all of your blacklists not work on Safebooru?
In any case, my suggestion is to clear your Safebooru cookie. Blacklists are stored in your cookie, so maybe something got messed up there.