Hadn’t she already given testimony on the subject in question? If I recall she refused to testify a second time because she had already done so.
Either way, with immunity granted, there's no Fifth Amendment peril there.
She claimed a lot of legally nonsensical things on stand so I'm not sure any of it passed any scrutiny. It certainly didn't with the judge.
https://www.washingtonpost.com/local/public-safety/chelsea-m...