Not working Bluetooth communication with HC-05

Hello everybody,
I must report problem that has begun in communication between modul HC-05 and my mobile phone.

My mobile phone:
Xiaomi Redmi 8
Android: 9 PKQ1.190319.001

I must introduce my apliaction: I try to create aplication, that will be able to control power supply controlled by MCU Atmega 328P. I have connected MCU Atmega with HC-05 Bluetooth module via Serial Interface, and HC-05 I have connected via Bluetooth with mobile phone. Communication worked, data flowed, but if I have downloaded new version of application (I changed only
appearance, not function), since that, HC-05 doesn´t reciving data.

I create another appliacation, for easy sending of data, I changed program in MCU to easy version that will be only able to probe if data flows or not, but It didn't help.

Connection of HC-05 and MCU is from electric view in good condition, I didn't change RX and TX, I try to change MCU, used another module, but i think that problem is in MIT App Inventor.

Has somebody the same problem as me?

Jaroslav Havel, Czech Republic, Technical University of Liberec

I just had some issues with an HC-05. actually a few HC-05s


I have been checking these examples and it works for me.
Baud: 9600