- If the icons are grayed out, it's because your controllers aren't switched on.
- If the icons aren't showing at all, it's likely that SteamVR is running in Safe Mode. Check your SteamVR status window to find out if that's the case, and see if there's a way to resolve the conflict.
The LIV Driver could also be missing/disabled! To check for either case, navigate to SteamVR → Settings → Startup/Shutdown → Manage Add-Ons.
If it is missing, try verifying LIV's contents in Steam.
If it is disabled, flip the switch to enable it and you should be good to go!