Thanks again Palliser. After exhausting all possibilities and redid the circuit multiple times I finally figured out the work around. I am suspecting it has something to do with the Serial Monitor on Mac. I inserted a line (cannot be a blank line) right before the while loop and both examples worked.
void loop()
{
Serial.println("-----");
while (Serial.available() > 0) {
CAN_MSG_1 = Serial.parseInt();
if (Serial.read() == '\n') {
Serial.print("Sent value= ");
Serial.println(CAN_MSG_1);
//delay(1000);
}
}
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