This one catches all of us out at some time or other…
The white balance is perfect on photo A, so you sync the settings to photo B… but it doesn’t change. So you try it again… and it still doesn’t change. Why?
As Shot is the key. If photo A is set to As Shot white balance, photo B will also be set to As Shot, not the same numerical values.
To solve it, select ‘Custom’ from the white balance dropdown, or shift the values slightly, and THEN sync with photo B, and your numerical values will then be copied.