So I've noticed this behavior across my devices, but some devices show all my spotify connect devices (HK Invoke, FireTV, Google Chromecast and Google Minis) and some show only a handful. I've had better luck on my wireless devices (iPads, iPhones) than on my PC (where I use the Win10 client). On my PC, only a few devices show up rather than all of them.
Appreciate any thoughts on this... it's been an ongoing issue for some time and I'm curious as to why it happens at all. Thanks!