Does anyone else have this issue? For some reason, the mobile website version of my wishlist doesn't show which games are currently discounted. It does seem to show the discounted price, but not the icon that shows you there is a discount.

Hah! I just wrote out a ticket to support on this very issue 5 seconds before coming on here and seeing your thread.
It's been like that for me for ages, so I finally decided to report it. You should too!

Yep, same here. Since it's not working for ages it's definitely not bug but feature:)

It's been like this since at least the redesign. I don't remember if it showed the discount or not before.