Timer1 CTC mode not resetting count

Projects Programming
1

I'm trying to drive stepper motors using interrupts but I'm having trouble getting the interrupt configured correctly.

Here is my initialization code for the interrupt

void timer1_init()
{
    // set up timer with prescaler = 8 and CTC mode
    TCCR1B |= (1 << WGM12)|(0 << CS12)|(1 << CS11)|(0 << CS10);
  
    // initialize counter
    TCNT1 = 0;
  
    // initialize compare value
    OCR1A = 100;
  
    // enable compare interrupt
    TIMSK1 |= (1 << OCIE1A);
  
    // enable global interrupts
    sei();
}

Here is my ISR

ISR(TIMER1_COMPA_vect){
    SET(MOTOR_PORT,LEFT_MOTOR_STEP); //set the pin high
    delayMicroseconds(3); //keep high for a bit
    CLR(MOTOR_PORT,LEFT_MOTOR_STEP); //set it low
}

No matter what i set OCR1A to it always steps at the same speed.

It isn't resetting TCNT1 like It should (if i'm reading the datasheet correctly).
I verified this by printing TCNT1 in the loop code and I am seeing values greater than 100.
Is my understanding of CTC mode incorrect or did i just miss something that i need to set?

Thanks