@vbPhil, glad you posted this. I am seeing the exact same thing. HA does not create a scene the same way as ISY does. It appears the ISY creates native Insteon links between all the devices in a scene, so that even if the PLM is removed, the devices still talk to each other. HA on the other hand just creates a link between the devices in the scene to the PLM, and gives it a group # for use in HA. So if the PLM is disconnected for any reason, the scenes no longer work. I like the way ISY does it much more, since I want my house to still work when the PLM is dead for some reason.
Maybe we can ask the Insteon plug-in leader in HA to add the creation of native links in the Insteon devices when HA creates scenes.