Dealing with this exact issue still, Croster theme.
Test and live stripe, both result in Uncaptured. Customer gets sent to the invoice being required to pay (again), once they pay it there, it works.
See this error in Stripe in API Logs. Secret key is provided, I've reset / regenerated it multiple times as well.
{
"error": {
"code": "secret_key_required",
"doc_url": "https://stripe.com/docs/error-codes/secret-key-required",
"message": "This API call cannot be made with a publishable API key. Please use a secret API key. You can find a list of your API keys at https://dashboard.stripe.com/account/apikeys.",
"request_log_url": "https://dashboard.stripe.com/test/logs/req_viiblah blah blah",
"type": "invalid_request_error"
}
}