Changing the Icon for a tile does not update the icon shown next to the tile in panel builder. BUT, the icon is updated on the Panel when in View mode.
For example, I changed the icon for a Wemo switch in the panel builder to the xmas tree icon. In panel Builder, the icon next to the item is still showing as a switch. But when I run the panel on my device, it is shown as the xmas tree icon.
Seems to be common to any icon I attempt to change to.
Customer support service by UserEcho