My forced character rename half-works then reverts

After not having played SWTOR in years, I've started playing again recently. All of my characters have a required character rename and all but one of them are working fine.

The one that isn't working says that the rename was successful and shows the new name on the character select screen. However when I enter the game with that character, the name overhead is still OldName_237498367. Conversely, chat messages that character sends show as NewName. Items that character had crafted show "Created by NewName." Story instances say that they belong to OldName_237498367.

When I log out of any character (whether by Logout or Quit), the character selection screen shows OldName again, and once again I am prompted to rename the character...starting the cycle over.

This character seems to be stuck between successful and failure in terms of renaming. How can this be fixed?