That is normal for different raw processing software to have different WB numbers. Each app has their own processing engine and develop profiles to render the raw data. You can test with different apps like Capture one, ON 1 Raw, and DxO and others.
I recall doing tests in 2005 2006 when I began shooting raw with several apps to decide which app I would choose. Even if I shot with a neutral grey card in the image and selected to click the I dropper from the individual card the RGB numbers were different.
See the screen capture below, its a test with, left to right, Olympus View 2 (camera software), Lightroom 4, and After Shot Pro the images were all corrected with the WB dropper of the individual apps and you can see the difference in the individual colors.
Thanks for the reply, but it doesn't answer the question I am asking. I'm aware that each processing software creates different valeus and interpretations of the RAW data. I'm not bothered about the numbers matching the values in camera, just consistency between the two cameras which I know to have the same WB profile. This is the problem here, all other processing software treats the two cameras the same and provides consistent values as a starting point, while Lightroom doesn't.
There appears to be soemthing in the formula used for the Z7ii which is creating an anomaly in how the white balance is displayed on import. The two cameras should show a consistent WB value, but they don't, which is the issue I am trying to solve.
Do you have the same default develop settings for both camera models?
By virtue of the fact that the initial mapping is different on both cameras, you'll never have a situation where applying set values to both will give exactly the same colour. Perhaps a color card (like the ColorChecker Passport) shot with both cameras in the same lighting would give you a start point for your colour (and a profile if necessary).
It is totally expected that two cameras (even the same make and modle) might show differences in WB which is just a metadata suggestion from a device (two devices in this case) that don't really 'measure' color. And further, the same CCT value (say CCT 5000K) is a number that defines a lot of possible colors; not just one.
You'll likely need to build your own WB off set for one or more cameras to get them to 'match'.