Still seems to be an issue. I'm using Samsung Internet on my phone and last week had this problem trying to add a product to my Wishlist. It's there as the page is first loading but vanishes when the product picture and Norton Shopping Guarentee appear. I found just clicking before the page finished loading worked fine but probably won't for anyone with a really fast connection. Looking now, it seems to be the case for every product I view!
Ian Chimp's workaround above for adding an item to the wishlist works great but it's quite a bit of faff compared to the normal simple click. I think there is a forum thread for reporting technical issues but I can't seem to find it now.
Edit: Just seen it's "Lovehoney Glitches" and Ian Chimp has already brought it up! 🙈