Thanks for the suggestions. I've tried different browsers on different equipment (Opera and Edge on Windows 10 on a laptop and a desktop, Safari and Chrome on an iPhone), and all fail to show the play and 3 dots icons on the Playlist page of "v3m.html"
I've tried clearing caches, although in most cases the browsers I've tried have never displayed that page before anyway; I'd missed the addition of this new mobile page until I downloaded the iOS app the other day.
I have managed to make the missing icons appear on Win10 by accessing the developer tools of the browser and disabling the "position: absolute;" line of the "#playlistTbody .darkRow .flex1, #browseRadioSection .darkRow .flex1" css instruction. This brings the icons into view from wherever they've been hiding.