THIS IS AN UNCONFIRMED SOLUTION TO THE BIG PROBLEM RECENTLY, PLEASE READ BELOW!
Hey everyone, I just came to let you know about my solution to the problem everyone is having about not being able to add contacts, message them, always being offline etc.
Skype runs using the Lync network, and if you use the same email that you do for Skype and MSN, you will run into a problem where your email will be categorised as a Lync email. For some reason, WLM 2012 doesn't like this, and you are unable to add the person or message the person who has a Lync email, and they will be seen as offline.
Currently, the only solution I know is to create a new e-mail using outlook, and using that as your MSN address. Your friends will need to do the same, unless they're account isn't linked to Skype/Lync.
If your account is unlinked, but theirs isn't, you wont be able to message them at all. All of them HAVE TO BE UNLINKED FROM LYNC/SKYPE. It must either of never logged on using Skype, or it must be a new email.
Personally, I have three emails. One for MSN, one for Skype and my personal email. It is very important that your MSN email and Skype email are different, from what I've explained before.
Again, I will need to get this confirmed, but this has been my only and best solution to the problem, and not only for me, but all of my friends who use MSN too.
I hope this helps, and that you can give me feedback to whether this worked or not.
EDIT: I found that you may also have to add each other using butterfly messenger after you and your friend gets a new email. Also, IT MUST BE AN OUTLOOK ACCOUNT. Other accounts don't appear to work to well with WLM 2012, especially if it's used for Skype at the same time.