No click, but it's clearly very firmly in there. I've used enough force to slide the PC across the table, and tried holding the back and it won't go in any further unless my hand started to indent the back of the case. It's hard to remove at that point except by pulling hard and very gentle wiggling. I've reseated it twice now and still no change. Nothing is broken yet, but I don't want to push any harder because it might.
Other people have had issues with the manufacturing tolerances of this cable. It's supposed to go all the way in and leave no gap, but I have a tiny gap and the top grills are showing.
I'm using a 4070 Ti Super rather than a 4080 or a 4090, so the issue for potential cable melt is lesser, but even so I'm not sure it's a great idea risking turning it on. Will it be fine to power up because the gap is tiny or should I try and get a new cable somehow (but then you're told not to use them if they don't come with your GPU or PSU bah)?