We always understood that a block would stop unwanted challenges. However, most of us don't use it much or at all. I have mostly seen it used on the forums.
Some users have apparently discovered recently that it is ineffective in some situations.
No one has determined the reason. Perhaps it is something they screwed up with the V3 coding updates.
http://www.chess.com/forum/search?keyword=block+glitch
If someone is being harassed by another member, they should just write an email to the staff ( https://support.chess.com/customer/portal/emails/new )and that person will be dealt with.
One of my opponents decided to Block a player for what appeared to be a legitimate reason.Despite the block they say they are still receiving unwanted chess challenges from that person.Is this a glitch? I understood that a block effectively cut off all communications including challenges?