Serial pins not enabled - Arduino 101

It seems like the default serial pins (pin 0 and 1) is not enabled on my Arduino 101.

The pins work as they should when declared as output pins and assigned with digitalWrite. However the UART signal on pin 0 and 1 is not initiated by Serial.Begin as it does on my other Arduinos. The TX/RX LED on the board do not blink either.

Do they need to be enabled in some other way? Do my 101 work as it should?

Serial is USB only. Use Serial1 for pins 0 and 1.