Blocked people, sometimes you see their tweets, sometimes you dont


I don’t really understand the blocking people feature. I have blocked people, the odd thing is that sometimes if I look at their timeline I cannot see any of their tweets and hopefully they cannot see my tweets… but other times I can see their timeline . This all happens when being logged in
Why is it that this keeps changing constantly? In theory when blocking someone, they shouldn’t be able to see your timeline and you shouldn’t be able to see theirs… sometimes I get a message on their timeline saying this user has not tweeted yet, and another day I can see their full timeline

go and figure that one out