Synchronization problem with Interrupt Service Routine (ISR)

Firmware
7

Thanks @rickkas7 . I followed the example you provided and implemented changes in my other project code. I remember now seeing this topic (atomically increment a variable in the ISR) in a thread with @chipmc but I did not utilize the concept until today:
https://community.particle.io/t/volatile-structures-and-eeprom/56865/5

I thought I would correct or "make better" the pseudocode I wrote earlier:

// Atomic variables - values are set and get atomically for use with ISR
std::atomic<uint32_t> pulseCount;

void isrTriggered() {
    // This increments the value atomically. Even if the ISR triggers
    // while we're resetting the value from loop, the count will
    // not be lost.
    pulseCount.fetch_add(1, std::memory_order_relaxed);
}

void setup() {
    ...
    pulseCount.store(0, std::memory_order_relaxed);
    pinMode(D3, INPUT);                          
    attachInterrupt(D3, isrTriggered, FALLING);
    ...
}

void loop() {
    static unsigned long lastCheck = 0;
    if (millis() - lastCheck >= 1000) {
        lastCheck = millis();
        // Take the value from and clear it to 0 atomically. Even if
        // the ISR triggers at this exact moment, "pulseCount" will either
        // be updated before reading (.fetch_and), or after setting to 0, but never
        // in the middle.
        uint32_t tempPulseCount = pulseCount.fetch_and(0, std::memory_order_relaxed);
        // process pulse count here
        ...
    }
    // all the rest here
    ...
}