P: Incorrect display shown after merging stacks

Hi, Experiencing a problem (bug) that started showing up in 4.2 and I have been told remains in 4.3 concerning merging stacks. Here is the scenario:

1) In Library Module, Grid view, I have several stacks all of which are collapsed. For the sake of argument, let's say one has 3 images and another has 4

2) Now, I want to merge the 3 stack into the 4 stack with the top image of the 4 stack being the top image of the new 7 stack.

3) I Select both the 3 stack and the 4 stack, making the 4 stack the active stack (brightest canvas)

4) Press Ctrl+G to "merge selected images into stack" - in this case the selected images are the two collapsed stacks

5) This folds the 3 stack into the 4 stack as it should

6) in the old days of LR (prior to 4.2) LR would then show 1 thumbnail representing the new 7 stack with the number 7 on it as it's stack count.

In the new days of LR 4.2, instead you see all 7 images in the grid, with all 7 of them having the number 7 on them as the stack count. In other words it's showing an expanded stack with incorrect stack postion numbers. To get back to normal, Click the 7 on the one image that should be the top of the stack which renumbers them all, then click it again to collapse the stack.