HI Deano, I see the error which is a null pointer exception which is almost certainly the cause. Note: You cannot consider the logging output to be in sequential order, just a Smartthings quirk.
I was gone for a few months and reading up on the new Smartthings app and found out that when they switch to the new app (and shutdown classic) the only supported communications will Zigbee and Zwave. That means any and all HTTP connected devices will no longer be supported. So there will be no integration
Because of this discouraging situation I don’t see any future in finishing this device handler for Smartthings (it was only a Beta), only for it to become redundant later this year.
So I’m going to put my energy into finding a different platform that supports MQTT.