In Firefox zoom will not work correctly, if you zoom in or out the complete scene will disappear. But strange if you embed the exported Koru html file in an iframe it will work... Here you can test it:
The original html file:
The file embedded in an iframe:
Using https or http makes no difference. In all other tested browsers (Chrome, Opera, Edge and the f******** Internet Explorer) it works perfect, only in Firefox it doesn't.
Customer support service by UserEcho