Hey Toby @MattyJSeely
Could you use the Find My Earbuds feature to check if sound is working on both Buds, by heading into your Galaxy Wearables app on your phone > select Find My Earbuds > tap the magnifying glass icon. This will make your Buds beep. But please do not wear the Buds whilst performing this step, as it can result in hearing damage.
If you're able to hear the beeping, it means the Buds are working fine. So, if this is the case, please update the app software by heading into Play Store, and once you've done this, head update the Buds by heading into the Wearable app > Earbuds Software update > Download and install.