This seems like a bug, let me explain why.
If you select a color, say 4800K, and then reopen the color picker, it should stay at 4800K. This consistency is important for artists who might want to make subtle adjustments to the Kelvin color. For example, if it was 4800K and you want to bump it up to 5000K, you’d need the original value as a reference.
While this might not seem like a big deal at first, you would expect that numerical parameters like these should remain consistent in most Windows applications, right?