This only happens on my Fire 10 7th gen. It does not happen on my Fire 8, same browser, same settings. Fully Kiosk Support just blanket-blames Android. I do have the proper Fire-only app for Fully Kiosk Browser. Everything is on it's latest version. I've even done a full reinstall of the table.
Pulling to refresh the page restores the icons.
This worked fine for a year when first set up, yet the icons stopped appearing 6 months or so ago. Basically the story of all home automation.
Customer support service by UserEcho