Arduino for STM32

did the trick.
Also see https://community.platformio.org/t/can- ... dfu/6431/7

You can set a new path in the batch file switching the Arduino java ahead of the system one. That's the solution described in the original post. @Mano: I was having the same issue, but after successfully uploading to the bluepill once, it now enumerates as "Maple 003" but not as VCP (USB ...