It is a known issue, that was discussed at length a while back. Basically, while working in ACES color space, just adding a control point in HSL curves will cause the highlights to clip. So, because the latest beta still works the same way, it got me thinking. May be I'm using ACES wrong? If this is indeed a bug, then it's kinda a huge one. And if it is a bug and it is a huge one, then BM would have fixed this huge bug prontissimo. I would even guess, that fixing such a bug would take a priority over something as pedestrian, as changing the "select all" button in the delivery page, no?