First, the card status is abnormal, such as degaussing the card, and the password is locked because of too many input errors. This suggestion is confirmed by the landlord calling his home service hotline.
Second, there is nothing wrong with the card. If the signal of POS machine is not good, the off-line transaction will fail.
Thirdly, if the landlord holds an IC chip credit card, because UnionPay has closed the downgrade transaction function, if the cashier still operates the transaction by swiping the card instead of inserting the card, it will not be available.
Fourth, the landlord card does not support transactions. For example, VISA single logo /JCB single logo card does not support UnionPay transactions, nor does it support some online transactions (not all POS machines can be used even if the acquiring bank is CCB).
Fifth, the credit card itself is insufficient. If this is the case, you need the landlord to pay back the money in the credit card before you can use it (you can use your mobile phone number reserved in CCB, edit the short message "3 13# in the last four digits of the card number" and send it to 95533 to inquire about the available credit cards).
If the landlord has other questions, you can ask.