I have been unable to use the invite on messenger feature on Outlook.com for several months now.

When I click "Invite to Messenger" on people.live.com, and type in their email address and submit, all I get is an error saying "This Page Is Temporarily Unavailable. We're sorry, there was a problem showing this page.  We experienced some technical difficulties retrieving the content."

I've also noticed that some contacts never appear online for me - despite them being signed in - and I cannot use the rooms feature on my Windows Phone 8 device - when joining a room from an invite it just says it cannot connect and that it is unavailable.
I have tried on multiple systems, internet connections, and web browsers, but the issue remains. The account in question is linked to a skype account and an xbox live account.
Are there any other steps I can take to resolve this?