javascript – unable to get response from promise.all()

I find that I cannot get the response when using promise.all.

The orders below should be an array

Promise.all(promises).then(function (orders) {
  console.log(orders); // nothing logged
});

Full code

let promises = markets.map(async (mkt) => {
  return new Promise(async function (resolve, reject) {
    return functionA(paramA)
      .then(resA => {
        return res.functionB()
          .then((resB) => {
            if (resB.length > 0) {
              return functionC()
                .then(resC => {
                  console.log(resC); // successfully logged
                  return resC;
                });
            }
          });
      })
      .catch(err => console.log(err));
  });
});
Promise.all(promises).then(function (orders) {
  console.log(orders); // nothing logged
});

How can I fix?