STM32 DFU not working through UART and USB

Advanced Solutions Debugging
15

And what happens when you only have

#define LED PB13
void setup() {
  pinMode(LED, OUTPUT);
}

void loop() {
    digitalWrite(LED, HIGH);
    delay(1000);
    digitalWrite(LED, LOW);
    delay(1000);
}

with the platformio.ini

[env:genericSTM32F411CE]
platform = ststm32
board = genericSTM32F411CE
framework = arduino

? That should try to use HSI, so not the external crystal. Does PB13 blink then?