After paying 30,000 yuan with WeChat overdraft card, all overdraft cards cannot be used for the following reasons.

1. There is a risk that the transaction does not go through the banking system and the credit card cannot be used.

2. This will also happen if the credit card payment exceeds the limit. Generally, payment cannot be made if the limit is exceeded.

3. It may be because the credit card limit of the cardholder is insufficient or the merchant does not support the use of credit card payment.

4. The credit card is in an abnormal state, such as being reported as lost or frozen.