This could potentially be a duplicate of Why does flag marking as helpful/declined not always correlate with moderator action?, but the timing makes me think maybe not.
There was a lengthy discussion about an answer that was going nowhere, so I flagged all ~20 comments. As soon as I finished flagging, the answer was deleted, and when I went to my profile (instantly when the post was deleted), all my flags were listed as helpful, but when I look at the now-deleted answer, the comments remain.
Do comment flags get auto-marked as helpful if the post was deleted? Or did a moderator instantly review all of my flags as helpful without removing them and I just didn't notice?