Find a chunk of text on a webpage, such as an article, and start reading through it with the arrow keys (with Quick Nav off). Press vo-shift-h,, then keep arrowing. Even though VoiceOver seems to move to the previous heading, the arrow keys keep moving you through the text you were reading. If you instead press vo-right just after vo-shift-h, you are moved to the element after the heading, as you'd expect.
Bug First Encountered
How often the bug occurs
I found that focus syncing is inconsistent in el cap as well. It sometimes works but fails for me eventually: doing a say all, for example, does not move the arrowing cursor.