ESP8266 Arduino and Rotary Encoder

I'm trying to use the sketch bellow to work with my WeMos D1 mini (ESP8266 Arduino platform) together with Rotary Encoder KY-040 or MJKDZ, and it's not working for some reason, but the same sketch is working great on the Arduino Uno (with different pin assignment - 2, 3, 4).

Can someone explain to me what is the issue with the sketch?

const int PinA = 14; // Used for generating interrupts using CLK signal
const int PinB = 12; // Used for reading DT signal
const int PinSW = 13; // Used for the push button switch


int lCnt = 0; // Keep track of last rotary value
volatile int vPos = 0; // Updated by the ISR (Interrupt Service Routine)

void isr_event ()  {
  static unsigned long lIsrTmr = 0; // Last Interrupt time
  unsigned long IsrTmr = millis(); // Interrupt time

  // If interrupts come faster than 5ms, assume it's a bounce and ignore
  if (IsrTmr - lIsrTmr > 5) {
    if (digitalRead(PinB) == LOW)
    {
      vPos++ ; // Could be +5 or +10
    }
    else {
      vPos-- ; // Could be -5 or -10
    }

    // Restrict value from 0 to +100
    vPos = min(10, max(0, vPos));

    // Keep track of when we were here last (no more than every 5ms)
    lIsrTmr = IsrTmr;
  }
}

void setup()
{
  Serial.begin(9600);

  // Rotary pulses are INPUTs
  pinMode(PinA, INPUT);
  pinMode(PinB, INPUT);

  pinMode(PinSW, INPUT_PULLUP); // Switch is floating so use the in-built PULLUP so we don't need a resistor

  attachInterrupt(digitalPinToInterrupt(PinA), isr_event, LOW); // Attach the routine to service the interrupts

  Serial.println(F("Starting..."));  // Ready to go!
}

void loop()
{

  // Is someone pressing the rotary switch?
  if ((!digitalRead(PinSW))) {
    vPos = 0;
    while (!digitalRead(PinSW))
      delay(10);
  }

  // If the current rotary switch position has changed then update everything
  if (vPos != lCnt) {
    // Write out to serial monitor the value and direction
    Serial.println(vPos);
    // Keep track of this new value
    lCnt = vPos ;
  }
}