That's true- Most of the other assets on sale also do not show up on the Sales and Bundles pages, although I guess I thought they would. The pages do show a mix of assets and games. I wonder if those particular pages are curated somehow?
I have encountered this issue with sales which is still present, but I'm unsure if it has any bearing on this.
Incidentally, after restarting the sales today I got a couple bundle purchases, so perhaps something did refresh somewhere?