I thought I had found every last attribute setting in Word. This stumps me.

I have a document where the 10 points of space before a Heading 2 gets
reduced as the space after for the heading paragraph above is increased. When
a normal pargraph is above, the 10 points of space is active. But when a
heading level 1 or 2 is above, the 10 points is absorbed into the space after
of the preceding paragraph.

"Don't add space between paragraphs of the same style" is not turned on. I'm
mystified.