Full-body tracking with trackers isn't working

Full-body tracking with trackers isn’t working even though I checked Waist + Feet inside the LIV Avatar Menu

You need to assign the roles for your trackers in the SteamVR settings. Go to the “Manage Trackers” portion of SteamVR’s settings and make sure the roles are set up for “Waist”, “Left Foot” & “Right Foot”.