Blizzard Panthar

Yesterday, I changed my display name from "Blizz" to "?????" with the username change ability under profile. It displayed for awhile, showed up in nearby chat properly, etc. Then, it vanished. Gone. Replaced by my whole account name. Due to how username changes work, I'm unable to change my name again for a week now. Am I not allowed to have such a display name, even though I see people with BUBBLE text names all the time? If that's the case, the timer on changing my display name could at least be reset. Bug, or not? Can my timer be reset?