I couldn’t manage to make this SmartApp work with the new SmartThings App so I created a small program to gather data from SmartThings to InfluxDB and Grafana. It does not run as a SmartApp but it is working very well for me.
If anyone is interested, you may find it here: GitHub - eargollo/smartthings-influx: A simple program to bring to Influx your SmartThings data through the SmartThings API. No SmartApp installation needed.