Bug: When a photo is cropped, the RGB values shown in the before/after mode are wrong for the before version (first numbers of the three RR/GG/BB pairs).
The RGB values shown for the before version is not from where the mouse cursor hovers over the photo, but from somewhere else, depending on the cropping used.
Steps to reproduce: 1. Create a simple black and white image in square format, the upper half black and the lower half white and import it into LR. 2. Go to crop mode (R) and crop away the upper quarter of the photo. 3. Leave crop mode and enter before/after left/right mode 4. Be sure that the current crop shows on the before version (see possibly related bug http://feedback.photoshop.com/photosh...) 5. Move mouse cursor slowly from bottom to top of the before or after version(which one does not matter) 6. You will see that the RGB values of the before version (first number in the three pairs) drops to zero (black) *before* you actually reach the black area in the upper half.
Interestingly, if you manage to provoke the above mentioned other bug and move the mouse cursor in the wrongly displayed before version, the RGB before-values match this wrong version. Contrary to that other bug, the wrong RGB before-values persist even after refreshing the display as described in my other post (e.g. zooming, changing to other photo).
Note: This applies to all 5 variants of the before/after mode, including the "before only" mode. And it also applies for images cropped on the left or right. And it seems to happen for all zoom stages.
This can be really annoying when comparing RGB values in before/after mode because you first have to reset the crop, make the tonal corrcetions that you need the RGB display for and then re-apply the crop when done.