Unable to get input from Wemos D1 PIR sensor

Question

I am using the script below to create a motion sensor using a Wemos D1 and a PIR sensor.

I'm using the ESP8266 Community board manager (V2.6.3).

THE PROBLEM

When I use the Wemos D1 R1 board no motion is detected at all.

When I use any of the LOLIN(WEMOS) motion is constantly detected even when the sensor is not connected.

I have tried multiple sensors and boards as well as double checking the wires used.

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

// Replace with your SSID, password and MQTT broker IP address
const char* ssid = "WIFI_NETWORK";
const char* password = "WIFI_PASSWORD";
const char* mqtt_user = "MQTT_USERNAME";
const char* mqtt_password = "MQTT_PASSWORD";
const char* mqtt_server = "MQTT_IP_ADDRESS";
const char* clientID = "sonfoff/pir";

const char* topic = "sonfoff/pir";
const int inputPin = D1;
int motionState = 0;
int i = 0;

WiFiClient espClient;
PubSubClient client(espClient);

void setup_wifi() {

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect(clientID, mqtt_user, mqtt_password)) {
      Serial.println("connected");
      client.publish(topic, "test", true);  
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {

  pinMode(inputPin, INPUT);
  Serial.begin(115200);
  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output


  setup_wifi();
  client.setServer(mqtt_server, 1883);
  while (!client.connected()) {
    reconnect();
  }
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  motionState = digitalRead(inputPin);

  if ( motionState == HIGH ) {
    digitalWrite(BUILTIN_LED, HIGH);
    Serial.println("Motion Detected");
    client.publish(topic, "on", true); 
    i = 0; 
  }

  while(motionState == LOW && i ==0){
    client.publish(topic, "off", true);
    Serial.println("Motion Stopped");
    i++;
  }

}