bme.begin() issue

// Arduino BME680 & Waveshare 2.9 epaper via SPI - NOT WORKING?!

#include <SPI.h>
#include <GxEPD2_BW.h>
#include <Fonts/FreeMonoBold9pt7b.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"


// SPI pin mapping (ESP32)
#define BME_SCK   18
#define BME_MISO  19
#define BME_MOSI  23
#define BME_CS    21
#define DISP_CS   5
#define DISP_DC   17
#define DISP_RST  16
#define DISP_BUSY 4

#define SEALEVELPRESSURE_HPA (1013.25)

// Display driver
GxEPD2_BW<GxEPD2_290_T94_V2, GxEPD2_290_T94_V2::HEIGHT> display(
  GxEPD2_290_T94_V2(DISP_CS, DISP_DC, DISP_RST, DISP_BUSY)
);


// BME680 via SPI
Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO, BME_SCK);

bool sensor_error = false;
float temperature, humidity, pressure, gas, alt;


// Chip select switching
void selectSensor() {
  digitalWrite(DISP_CS, HIGH);
  digitalWrite(BME_CS, LOW);
  sensor_error = false;
}

void selectDisplay() {
  bme.endReading();
  digitalWrite(BME_CS, HIGH);
  digitalWrite(DISP_CS, LOW);
}

// Read sensor data
void readValues() {
  selectSensor();
  //if (!bme.performReading()) {
    //sensor_error = true;
    //Serial.println("Error reading from sensor!"); }
    //return; }

  delay(400);
  //bme.endReading();
  temperature = random(-15, 40);
  humidity    = random(0, 100);
  pressure    = random(0, 100);
  alt         = random(100, 400);
  Serial.print("Sensor values: ");
  Serial.print(temperature); Serial.print(" °C, ");
  Serial.print(humidity);    Serial.print(" %, ");
  Serial.print(pressure);    Serial.println(" Pa");
}

// Update display
void displayValues(int16_t x, int16_t y, int16_t sep) {
  //if (sensor_error) return;
  selectDisplay();

  display.setRotation(1);
  display.setFont(&FreeMonoBold9pt7b);
  display.setTextColor(GxEPD_BLACK);
  display.setFullWindow();
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    display.setCursor(x, y);
    display.print("T: ");  display.print(temperature, 1); display.println(" C");
    display.setCursor(x, y + sep);
    display.print("H: ");  display.print(humidity, 1);    display.println(" %");
    display.setCursor(x, y + sep*2);
    display.print("P: ");  display.print(pressure / 100.0, 2); display.println(" hPa");
    display.setCursor(x, y + sep*3);
    display.print("Alt: "); display.print(alt, 1);        display.println(" m");
  } while (display.nextPage());

  Serial.println("Display updated.");
}


// Setup
void setup() {
  Serial.begin(115200);
  delay(100);

  // Start SPI manually
  SPI.begin(BME_SCK, BME_MISO, BME_MOSI);

  // Configure CS pins
  pinMode(BME_CS, OUTPUT);
  pinMode(DISP_CS, OUTPUT);
  digitalWrite(BME_CS, HIGH);
  digitalWrite(DISP_CS, HIGH);


  // Initialize display
  selectDisplay();
  display.init(115200, true, 2, false);

  // Clear display once
  display.setRotation(1);
  display.setFullWindow();
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
  } while (display.nextPage());

// Problems with initializing the sensor: as soon as it is enabled,
// the display stops working. Without initializing the sensor, it doesn't provide any values
// because it ends up in "Error reading from sensor!".
// Maybe initialize the sensor before initializing the display? -> Tried it, not working...

// The problem is bme.begin(). I thought it was the combination of bme.begin() and bme.performReading()
// because bme.performReading() is never stopped. Tried using bme.endReading(), but it doesn't help.

// The display only works if bme.begin() is commented out.

  // Initialize sensor
  selectSensor();
  //bme.begin(); // Thats the problem!!!
    //Serial.println("BME680 not found!");
    //while (1);
  //}

  //bme.setTemperatureOversampling(BME680_OS_4X);
  //bme.setHumidityOversampling(BME680_OS_2X);
  //bme.setPressureOversampling(BME680_OS_4X);
  //bme.setIIRFilterSize(BME680_FILTER_SIZE_3);

  Serial.println("Setup complete.");
  delay(2000);
}

// Loop
void loop() {
  Serial.println("\nNew cycle...");
  readValues();
  displayValues(20, 20, 20);
  Serial.println("Waiting 30 seconds...\n");
  delay(30000);
}