While the discussion is about not being able to program STM32's with STlink, it turns out that the reason it doesn't work is because the CPUID was different than that which would be read from a genuine STM32 part. The link below, second page, has more on these boards. there may of course be versions of the chip with correct markings, not STM32) that that also don't work. I have concluded that while the boards were sold as STM32F103C8T6 system minimum boards and the chips are labelled as STM32F103C8T6, they are in fact something else with STM32 markings. I was have been having problems getting USB to work with recent STM32F103C8T6 system minimum boards, getting 'device not recognised' messages and 'device descriptor request failed' message in device manager (Win 10).