429 RESOURCE_EXHAUSTED after buying prepaid credits

Hello,

I have a problem with Gemini API Billing.

My billing page shows:

  • Credit balance: VND 1,997,391
  • Billing Tier: Paid 2
  • Prepay enabled

However, every generateContent request returns:

429 RESOURCE_EXHAUSTED
“Your prepayment credits are depleted.”

The API key is valid.
The following request works:

GET /v1beta/models

But this request fails:

POST /v1beta/models/gemini-2.5-flash:generateContent

Project ID:
gen-lang-client-0954537..

Billing Account ID:
013E6D-114DFE-A7F…

Could you please check whether my prepaid credits have been synchronized correctly?

Thank you.