Getting key prop warning in React, even though key is set

Have you tried adding a key to the <th> tag?

         <tr>
            {_.keys(this.props.list[0]).map(function (key) {
              if (key !== 'attributes') {
                return <th key={key}>{key}</th>;
              }
            })}
         </tr>

I ended up solving it when I realized because I had a <React.Fragment> which also needs a unique key.