Steam Friends

I can add other people and they appear as pending but the person I want to add does not.

Maybe they already blocked you so you can't befriend them anyway?

More than likely, it means that they've blocked you. I know this because I've been trying to add someone who ran a giveaway that I won a couple of days ago, but they refuse to add me.

I don't know, could be the blocking part, but also Steam bugging out. As I have recently experienced it a lot that someones added me, I accept, and then the person is listed as invited (while they added me in the first place). After a restart of Steam the friends list is as it should, and I can also send messages while they are 'pending acceptation'.

Not sure if this has anything to do at all with your problem, but just thought I'd mention it as Steam doesn't always work the way it should I suppose. :)

I'm sure it's just a glitch.