I've set up two products with an attribute "ColorScheme". It's multiselect so that I can set one or several colors in the ColorScheme field.
Now, if I set one product to Red, Green and the other to Blue, in the front end Layered Navigation under ColorScheme I get, as expected, Red, Green and Blue, each showing (1) hit. (Two of these obviously select the same product.)
But if I set the two products to have overlapping lists, Nav seems to break. If I set one product to Red, Green and the other Red, Blue, then in Layered Nav I get Green (1) and Blue (1), but not the Red (2) item I expected.
Is there a setting somewhere I have set wrong?
(I have flushed pages, and reindexed, and tried multiple different attributes and combinations, and this behavior is consistent.)