I cannot connect to the ESP32 device, although the ESP32 device is still detectable by the software "BLE Scanner"

[HuuThanhBui]

When I came to the lesson "BLE GATT Write" (link: https://www.learnesp32.com/20_ble-gatt-write) Although I copied the author's sample code and loaded it into the ESP32 device, when I using the software "BLE Scanner" (the author used this software in the lesson to scan BLE devices), the software can only see my ESP32 device, but cannot connect (Read, write information to callback function).

This is the image when the software detects the ESP32 device (name of device is: "MY BLE DEVICE")

This is the image when the software connects to the ESP32 device

Here is my project link: https://drive.google.com/file/d/1yo7jAUtWQ6I8MZ81gAQa41cVNeJG7FoC/view?usp=sharing

I have tried many ways and tried to find the cause but still no success!
Looking forward to hearing from you soon!
Thank you guys for the help!