I'm not sure if this only affects OSX but I can reproduce it every time there.
Steps to reproduce:
- copy a hex color code from a text document
- open the color picker and select the current hex letters
- press command V. It does not paste the hex and doesn't seem to do anything.
Workaround (also buggy)
- select the current hex letters in the color picker
- right click and choose paste
- note that the color has not changed in the color picker. To get the color to actually change you have to press backspace then retype the 6th hex character.