TinyWireS - Slave Code on ATTiny85 - Request Method Messed up from Interrups?

Projects Networking, Protocols, and Devices
1

I've built a frequency/counting device with an ATTiny85.. It seems to be working, but after a handful of reads from the Master device, the ATTiny start to send junk.. I think this is because the byte ordering is getting mixed up...

SendCount is initialized to 0 in the Setup() Method.

Here's my Request method:

volatile unsigned long Data1;//this is the data from the frequency method
volatile byte SendCount;
volatile uint8_t sendByte;

void requestEvent()
{  
  
  SendCount++; //increment this
  switch (SendCount)
  {
    case 1:
      Data1 = TinyFrequencyCounter.GetHz();
      sendByte = Data1 & 0xFF;
      break;
    case 2:
      sendByte = Data1 >> 8;
      break;
    case 3:
      sendByte = Data1 >> 16;
      break;
    case 4:
      sendByte = Data1 >> 24;
      SendCount=0;
      break;
  }

  TinyWireS.send(sendByte);
}

I've tried a few different ways to count frequency I am counting interrupts until I get a timer 1 overflow. it's accurate enough for my purpose at this point

ISR(PCINT_VECTOR)
{
  PulseCount++;
}

ISR(TIMER1_OVF_vect) //Core Build Options.H line:112 - change from 1 to 0
{
  //The timer have overflowed get the pulse count;
  GatePulseCount = PulseCount;
  PulseCount=0;
}

Are the ISRs affecting the Request Event? How can I fix this?