I'm using the new nav, and I usually using the recommended tags option. Today, I thought I'd switch it up a bit and look for questions in any of my favorite tags, so I changed the tag options to "favorite tags" and it showed any new questions in my favorite tags. But when I switched back to "recommended" the highlight on questions in my favorite tags no longer had highlight applied to them.
As you can see, the top 7 posts should have been highlighted, but are not. The final (8th) post in the screenshot does not match any of my favorite tags and correctly lacks highlight.
This only happens when switching from "favorite" tags and back. The other tag options (like "all" or "custom") don't seem to mess up the highlight. And refreshing the page also fixes this problem.