"Could it be because of the EMV chip? I used to have problems with using my Visa card with just a magnetic stripe in China, but since receiving a new card with the chip, I have not encountered any problems."
I've come across places that could not accept VISA/Mastercard unless it was a domestic VISA/Mastercard. Don't ask me to explain why. The logo they post makes no "China Cards Only" distinction.
In my case, I have a RMB credit card from the Hang Seng Bank in Hong Kong that has a UnionPay Logo. That is usually good enough.