If you are experiencing issues sending or receiving messages via Skype, you can rest assured that the app isn't only being terrible for you, as this is a problem affecting other users as well.
In a short post on the Skype Heartbeat blog, Microsoft states that it is aware of "a problem, where users may not be able to send or receive Skype chat messages", and that the engineering team is working to find a solution.
No indication was given as to when the problem started, nor has the dedicated Twitter handle, @SkypeSupport, been updated to reflect that the issue is even present.
This article will be updated as soon as there is more information regarding the timeframe of events, or details of possible solutions being implemented.
Update: As of 14:36 GMT (10:36 AM ET / 7:36 AM PT), the issue has been fully resolved.