The Spark Preprocessor is at it again! By disabling the preprocessor (and remembering to include “application.h”) I was able to get your exact code working
#pragma SPARK_NO_PREPROCESSOR
#include "application.h"
bool turnedLeft = false;
bool turnedRight = false;
unsigned long lastChange = 0;
void setup() { }
void loop()
{
if(turnedLeft || turnedRight)
{
lastChange = millis();
if(turnedLeft) { }
else if(turnedRight) { }
}
}