[SOLVED] analogRead() stops working when using any WiFi library on esp32

I’m trying to make a simple voltage logger using a voltage divider and a ESP32 dev board. The voltage is read and calculated perfectly if that’s the only bit in my code, but as soon as I introduce the wifi functionality (WiFiManager.h or ESP8266WiFiMulti.h) any analog pin that I read using analogRead() always returns 4095.

Code follows, any help appreciated!

// LED will blink when in config mode

#include <WiFiManager.h> // https://github.com/tzapu/WiFiManager

//for LED status
#include <Ticker.h>
Ticker ticker;

#ifndef LED_BUILTIN
#define LED_BUILTIN 2 // ESP32 DOES NOT DEFINE LED_BUILTIN
#endif
#define uS_TO_S_FACTOR 1000000
#define TIME_TO_SLEEP 30 //The seconds to sleep
#define BATT_VDIV_PIN 27 

int LED = LED_BUILTIN;

void tick()
{
  //toggle state
  digitalWrite(LED, !digitalRead(LED));     // set pin to the opposite state
}

//gets called when WiFiManager enters configuration mode
void configModeCallback (WiFiManager *myWiFiManager) {
  Serial.println("Entered config mode");
  Serial.println(WiFi.softAPIP());
  //if you used auto generated SSID, print it
  Serial.println(myWiFiManager->getConfigPortalSSID());
  //entered config mode, make led toggle faster
  ticker.attach(0.2, tick);
}

float get_batt_voltage() {
  int v=0;
  v=analogRead(BATT_VDIV_PIN);
  Serial.println(v);
  return v;
}

void setup() {
  WiFi.mode(WIFI_STA); // explicitly set mode, esp defaults to STA+AP
  // put your setup code here, to run once:
  Serial.begin(115200);
  
  //set led pin as output
  pinMode(LED, OUTPUT);
  // start ticker with 0.5 because we start in AP mode and try to connect
  ticker.attach(0.6, tick);

  //WiFiManager
  //Local intialization. Once its business is done, there is no need to keep it around
  WiFiManager wm;
  //reset settings - for testing
  //wm.resetSettings();

  //set callback that gets called when connecting to previous WiFi fails, and enters Access Point mode
  wm.setAPCallback(configModeCallback);

  //fetches ssid and pass and tries to connect
  //if it does not connect it starts an access point with the specified name
  //here  "AutoConnectAP"
  //and goes into a blocking loop awaiting configuration
  if (!wm.autoConnect()) {
    Serial.println("failed to connect and hit timeout");
    //reset and try again, or maybe put it to deep sleep
    ESP.restart();
    delay(1000);
  }

  //if you get here you have connected to the WiFi
  Serial.println("connected...yeey :)");
  ticker.detach();
  //keep LED on
  digitalWrite(LED, LOW);
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(1000);
  Serial.print("Voltage: ");
  Serial.println(get_batt_voltage());
}

After re-reading an article I found ESP32 Analog Input with Arduino IDE | Random Nerd Tutorials I noticed that only some ADC pins are available if wifi is used.