Error in the 7.0 RPM SKD : glTF extension KHR_materials_ior is not supported

When loading Full Body XR avatars into the project I get this error:
Bones do not match bindpose. UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

When checking the loaded .glb, I see this error:
glTF extension KHR_materials_ior is not supported