RTClib hangs on nrf52 Bluefruit Sense

[exipilis]

Hardware:

nrf52 Bluefruit Sense
https://www.adafruit.com/product/4516
with male headers.

Adalogger RTC
https://www.adafruit.com/product/2922
with female headers, CR1220 battery and miscroSD card inserted.

Arduino IDE 2.0.4

RTClib version 2.1.0

Test code:

#include "RTClib.h"

RTC_PCF8523 rtc;
void setup() {
  Serial.begin(115200);
  rtc.start();
}

void loop() {
  Serial.println("test");
  delay(200);
}

Device hangs, not recognized as USB port on both Mac and Windows.
I have to press reset twice to turn DFU mode.

If I don't use RTClib, everything works fine.