@io-explorer: Are you making sure to stay within the Bluetooth connection range of around 10m? If so, can you try disconnecting the watch from your S8, then reconnecting it via the following steps?
- Open the Galaxy Wearables app on your phone > Select the side menu icon > Disconnect > Select 'Confirm' when prompted. Now, close the app and re-open it, and follow the on screen prompts via 'Start The Journey'.
If the problem persists then, on your S8, go to Settings > Apps > Galaxy Wearable > Storage > Clear Cache. It would also be worth checking for an available update by going to the Galaxy Wearables app on your phone > About Watch > Update Watch Software > Update Now.