P: White Balance Eyedropper Tool No Longer Working Properly

So, if I understand correctly, aside from the incorrect RGB values shown (for which a bug is filed). The issue is that the WB Loupe, while applying the white balance as-expected, based upon the scale slider setting, is not modifying the percentages shown in the WB loupe?  This makes it more difficult to choose the area to click upon?

On the Mac OS (El Capitan) this behavior is still the same as it was in LR 4.4. It appears that this behavior has not changed. If you can demonstrate otherwise, I would need your OS version and the Lightroom version where the Loupe tool is using the greater than 5x5 area for calculating percentages so I can verify. Can either of you provide that? If we can show it is a regression in behavior, I can file it as a bug. Otherwise, we are looking at making more of a feature request to get the changes implemented. 

It sounds like you might want to request the "change in the sampling size area" as a new Idea. 

I agree. The WB correction applied to the Temp and Tint settings is correct and uses the the actual Scale setting area and not a fixed 5x5 area. Only the RGB numbers displayed in the eyedropper tool are calculated using a fixed 5x5 area. The displayed value should be calculated using all of the area selected by the Scale setting to avoid confusion.

Exactly.

Exactly.

Thanks Steve

I just posted similar results a few seconds ago and concur with your findings on what area the WB tool is using to set the WB when you click.  This may not be considered a bug but it is an unintuitive design.

  Rikk Flohr wrote "The active white balance sample area is limited to a 5x5 grid.  The loupe was modified to show greater detail but does not affect sampled pixel area size."

I agree the sample area for the number display "in the tool" is a 5x5 grid no matter what size the grid is  but the WB set when you click is set from the 17X17 (or other) size grid.  You can easily test this by setting the tool to 5x5 and set the WB, do a CTRL-Z and then set the tool to 17x17 and set the WB.  (the tool is NOT moved}.  The WB numbers for the two sizes in the Develop Panel will be different if your sample area has a lot of changes. 
If this is by design it is very unintuitive.  Beings Lr is reading the pixels from the larger tool to set the WB it should be easy to reflect this is the numbers the WB tool is displaying when the size is changed.  

"So the result is a 5x5 average for the % both under the WB dropper area and under the histogram." Yes.

"But the WB is still dependent on the full area, right?" Yes.

What's ironic is that viewing my original posted screenshots it appears the central pixel RGB value is what's being displayed....just as you stated at the LR forum post. That was with LR CC 2015.3. I can't duplicate this behavior with LR CC 2015.6.1. So is this a bug or an engineering change implemented after LR CC 2015.3 (6.3)?

In my opinion a single pixel reading has no practical value as I stated in my original request here: https://feedback.photoshop.com/photoshop_family/topics/white_balance_eyedropper_tool_option

The WB eyedropper RGB values are useful when measuring different areas of an image for WB consistency or even for color matching portraits and product shots. Knowing "exactly" what area is actually being measured (i.e. averaged) is important. All that needs to be done to fix this is to display the averaged RGB value for the Scale setting being used.