ICBC UnionPay credit card testing report just today:

1. USPS (post office) - Accepted as PBOC native chip as reported by others. Interesting that I have to sign for $3.

2. Safeway - NOT PBOC chip native
Gave error on contactless, then again on chip, prompting me to swipe; however, I wasn't interested in swiping the UnionPay, so I inserted a different chip card (MasterCard) and it accepted that as usual.

3. Target - NOT PBOC chip native
Gave error on contactless, then again on chip, prompting me to swipe; however, I then tried to insert a different chip card (MasterCard) and it ignored it, even after reinserting to be sure it was getting good contact; I swiped the second chip card (MasterCard) & it worked.
Conclusion: Once a Target terminal prompts you to swipe, it can't accept anything but a swipe, no matter what card you use. This behavior is thus restrictive because you can't switch gracefully to another payment type.