I’ve been able to clear the cache using the following steps:
- Enable remote WebView debugging in the app settings
- Enable USB debugging in the Android settings
- Connect with a USB to PC
- Download and install Chrome web browser on the PC
- Navigate to chrome://inspect URL
- Open the companion app on the phone again
- Connect (aka inspect) to the webpage
- In the Application tabs of the chrome Dev tools find the Service Worker and unregister it
- Refresh the webpage using the refresh button in the top left corner of Chrome
- Uninstall and delete the Chrome web browser (optional)