Why won't my promise.all return data even though it works - promise

Question

I am running the following code:
let Payment = relevantWaitList.map(e => {
stripe.paymentIntents.create({
amount: Math.round(e.totalCharge * 100),
currency: currency,
description: `Resale of ${eventData.title} refunded ticket`,
// customer: customerStripeID,
payment_method: e.paymentMethod,
off_session: true,
confirm: true,
application_fee_amount: Math.round(e.applicationFee*100)
}
,{
stripe_account: organiserStripeAccountID,
}
)
})
Promise.all(Payment)
.then(data => {
console.log('promiseall payment res', data)
}).catch(err => {
console.log('promise all payment fail', err)}
Which is returning the following:
promiseall payment res undefined
Despite it returning undefined, the promise.all is working - the stripe payments intents are created.
When I change to promise to include the .then within the map (using the code below), it console logs fine but I would prefer to play with the data after all promises have been completed.
What am I missing?
let Payment = relevantWaitList.map(e => {
stripe.paymentIntents.create({
amount: Math.round(e.totalCharge * 100),
currency: currency,
description: `Resale of ${eventData.title} refunded ticket`,
// customer: customerStripeID,
payment_method: e.paymentMethod,
off_session: true,
confirm: true,
application_fee_amount: Math.round(e.applicationFee*100)
}
,{
stripe_account: organiserStripeAccountID,
}
)
.then(data => console.log('data within map', data))
.catch(err => console.log('err within map', err))
})

Answer 1

Your .map() callback does not return anything which means that .map() will just return an array of undefined, giving Promise.all() no promises and no data to use.
What you need to be passing Promise.all() is an array of promises that each resolve to a value, then Promise.all() will return a promise that will resolve to an array of those values. In this case, you have garbage into Promise.all() and therefore garbage out.
So, your .map() callback should be returning a promise that resolves to the value you eventually want.
Assuming stripe.paymentIntents.create() returns a promise that resolves to a value you want, you just need to add a return statement:
let Payment = relevantWaitList.map(e => {
// ******* Add return on next line *********
return stripe.paymentIntents.create({
amount: Math.round(e.totalCharge * 100),
currency: currency,
description: `Resale of ${eventData.title} refunded ticket`,
// customer: customerStripeID,
payment_method: e.paymentMethod,
off_session: true,
confirm: true,
application_fee_amount: Math.round(e.applicationFee*100)
} , {stripe_account: organiserStripeAccountID,
});
});

Answer 2

As mentioned in the answer from #jfriend00, your map callback does not return anything.
You need to return the Promise object for each iteration
const payments = relevantWaitList.map(e => {
return stripe.paymentIntents.create({
// your props
});
});
The payments variable now contains an array of promises. You can use Promise.all() now
Promise.all(payments).then(data =>{
// play with data here :)
});