Stripe Auto-Payment does not working properly

I am encountering an issue with Stripe’s auto-payment process.

I need to create Stripe subscriptions in the unpaid state, setting the first payment date in the future. I can successfully create the subscription and set the future date using the trial_end parameter.

However, when the time comes for Stripe to process the automatic payment, the payment doesn’t go through properly — instead, Stripe creates the invoice in a draft state. As a result, the invoice.payment_succeeded webhook also fails to trigger and send the request to our website.

Below is create subscription request parameter:

API: https://api.stripe.com/v1/subscriptions

Method: POST

Authorization / Header: I am sending it correctly

Request Parameter:

trial_end:1746253519
items[0][price]:`my plan value`
customer:`stripe customer id`
proration_behavior:always_invoice
collection_method:charge_automatically
default_payment_method:`default payment id`

Note:
The same process works correctly when I create a Stripe subscription with a paid status — in that case, the auto-payment runs successfully, and the webhook (invoice.payment_succeeded) properly sends the response to our website.

I also tried modifying the request by adding the billing_cycle_anchor parameter, but I’m still facing the same issue.

Can someone help me understand what might be wrong with the parameters in my subscription creation request?

Thank you.