Seems legit. There can't be all that much spoken Iranian in the training set(s) of these models, so it makes sense they don't know how to do it.

I've been using ChatGPT to learn Persian (as a third language) for more than a year now (along with a heavy use of Anki), and it's incredibly useful and surprisingly good, for about everything: romanization, OCR from screenshots, deep explanations of complex and subtle stuff, etc.