Having trouble using RTC if I set an ISR for a 1 second timer
In the Arduino you don't have control how are some essential parts implemented.

For example delay function requires interrupts to be enabled or it'll be deadlocked (for sure).

Serials are little bit better, it'll be working until send buffer gets full. For devices with small RAM it's 16B only! And your traceDebug is little bit longer.

In general ISR should be as short as possible and it's mainly used for setting some flag to be handled in main loop later.

volatile bool flag = false;

ISR(...) {
  flag = true;
}

int main() {
  init();

  while (1) {
    if (flag) {
      do_something();
      flag = false;
    }
  }
}