Steps to reproduce and result: Using the curves smart filter on a smart object, the eyedropper tools for black, mid, and whitepoint do not respond or rarely respond. When double clicking the eyedroppers to pick from the color picker, this also has no effect on the curves effect, as it should.
I have found that using the eyedroppers in an adjustment layer also initially do not seem to do anything. I do see the curves change (so they do actually work), but I do not see the image change. I need to toggle the adjustment layer on and off to see the effect on the image.