As it is, I can't get my adjustment layer to apply to the layers I want because when I get them to clip for one layer, they stop working (they no longer change anything for any layer). If I hide the background layer, they stop working. This has been incredibly frustrating. I recently set my backgrounds layers as gray in my document presets for figuring out colours and I have a hunch that might have something to do with it.
It appears to have something to do with layer opacity. If opacity is too low the adjustment doesn't seem to alter anything. In other words, it seems if there isn't enough of a histogram to read, there's not enough histogram to apply an adjustment to. At least that's how it appears to me.
Low opacity layer....
Same adjustment, higher opacity layer (all I did was toggle layer visibility):
Side by side under the same adjustment layer:
The only difference is I boosted how opaque one layer was (via copies and merging).
And clipping works as expected with the higher opacity layer:
Note this low opacity seems to limit several adjustment layer types, not merely the curves.
I, personally, would use a Color Overlay Layer Style rather than an adjustment layer here, but that's merely my preference - and I realize your posted images may not be the actual files you are working with. The Layer Style doesn't appear to suffer from this limitation at all.