I have been conversing with a well-known user here about mastering an album.  He suddenly stopped answering my PMs.  My PMs seem to send but they are not in my Sent folder.  The user I was talking to had previously mentioned that his folders were messed up.
 
Does anyone know of an issue with PMs?
 
By the way, if you are the user in question, please contact me.

Just sent you a test message.

Also sent a test message, but I'm away from home and using an ancient XP machine because there's no wi-fi and I don't know the password to connect to the cable modem. If anything gets in or out of here, I'll be pleasantly surprised...

The default behavior for PM's is that they do NOT automatically save a copy in your Sent folder.  There is a check box you have to check if you want your outbound message saved to your Sent folder.
 
Please note that I don't send too many Private Messages, but the above is how it worked last time I sent one.  :)
 
I have occasionally had stretches of time (a few hours), from time to time, where I couldn't send Private Messages.  I just figured it was due to some sort of either maintenance at their end, or some issue that they eventually picked up on and reset, but each time - some time later - I was again able to send private messages.
 
Bob Bone
 

When I send PMs, some appear in my sent folder, some do not. I have never toggled any checkbox for this - it just seems to be random.

PMs have been exchanged all seems working.