When changing the color label (while a filter only showing images with an already existing color label is active), the change sometimes affects more than one image at a time.
Steps to reproduce:
Create new catalog, set AutoAdvance off
Import 6 images into the catalog
Go to AllPhotographs view
Select all 6 images using Ctrl-A
Click on label Red in the toolbar
Select Attribute Filter, only showing images labeled Red
Select first image only
Click on label Purple in the toolbar -> Image1 disappears, because Purple was assigned which does not match filter Red -> Selection is set to 2nd image automatically
Repeat for each of the 6 images -> sometimes (often), 2 images disappear because Red is removed from the first image worked on, and Purple is assigned to the next image automatically.
This behaviour is sporadic, but often enouth it can be called reproducible. It can can occur on any given image in the set or not, sometimes it happens on the 1st image already, sometimes on the 2nd, 3rd or 4th and so on, sometimes not at all. I am able to reproduce it about every second time I try though.
I've recorded a little screen capture with showing the behaviour here. In the example, when assigning purple to Image3, Image3 and Image4 disappear from the filter, because Image3 looses its label and Image4 gets purple assingned to it.