Thanks for flagging this up Ian, its affecting me too so looks like a widespread issue.
- If you send a PM to the recipient and type their full username in exactly, then the message does get through.
- Clicking on a persons usernmae (on one of their posts) and then selecting 'Send private message to X' doesn't put that persons username in the 'To' box.
- Typing in a partial name in the 'To' box doesn't seem to be auto-completing the possible users anymore.....
We will let you know when its fixed