I used ESP-IDF v4.4-beta1, Arduino 2.0.2 for and M5Core2-Library ("0.1.0" = newest version, I also checked 0.0.3). The Arduino libraries I got from "https://github.com/espressif/arduino-esp32.git" and the M5Core2 Library I loaded from "https://github.com/m5stack/M5Core2.git".

I can initialize the M5Core2, write text on the screen and connect to wifi. If I activated the SD-Card I got an error: "A stack overflow in task main has been detected."

I looked for the cause and it are these calls:

bool SD_Enabler = true;
M5.begin(true, SD_Enabler, true, false, kMBusModeInput); 
   -> SD.begin(TFCARD_CS_PIN, SPI, 40000000);
      -> if(!sdcard_mount(_pdrv, mountpoint, max_files, format_if_empty)){
          -> FRESULT res = f_mount(fs, drv, 1);

The reason for the stack challenge is f_mount.
There are only two parameters for this function:

FATFS* fs;
char drv[3] = {(char)('0' + pdrv), ':', 0};

The value for drv is "0:" and seemed okay. The parameter fs was initialled some lines one before without an error:

  esp_err_t err = esp_vfs_fat_register(path, drv, max_files, &fs);
    if (err == ESP_ERR_INVALID_STATE) {
        log_e("esp_vfs_fat_register failed 0x(%x): SD is registered.", err);
        return false;
    } else if (err != ESP_OK) {
        log_e("esp_vfs_fat_register failed 0x(%x)", err);
        return false;
    }

I didn't know what happened. Have anyone a good idea?