I character cannot send any item to other character from same account.

Greetings to you all
I have returned after a long time and noticed that my characters have been moved from Valefor to Asura and now I cannot send any item whatsoever to my main character, nor can my other accounts send it to my main character. However, they can send it to each other.

The sending service box will not even accept their names and the same happens when I tried to send something from those characters to my main character.

I already checked the files, deleted files to force an update, and even reinstalled the game but nothing seemed to fix that.

Since I have sent some items to those other characters I no longer have access to them since there is no communication between them and the main character.

Strange as it may sound, those other secondary characters can exchange items just fine but it is not true when I try to send items to my main character.

I'm truly sorry to bother you about that, but I tried everything I could and all the options I had. I appreciate any insight on how I could fix that.

Thank you.

This sounds like exactly what I would expect if the chars are on different servers. If you sell something to yourself on AH, can your other toons see it in AH history?

All of the involved characters need to be on the same server.

Further, though this may not be related, some items are account bound and can only be sent within an account. You mentioned using different accounts, so it could be such an item that's only sendable within the same account.