Waiting for all target devices to come online (Windows 10, Android Studio 4.1, all SDK is updated)

Hi, guys, I'm developer with big experience but newbie in Android. I have installed to my Windows 10 absolutely fresh Android studio
Android Studio 4.1.1
Build #AI-201.8743.12.41.6953283, built on November 5, 2020
Runtime version: 1.8.0_242-release-1644-b01 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Windows 10 10.0
And a lot of various SDK, all is fresh releases.
Than I have downloaded test project (I select sunflower). And three days I can not start it.
I learn a thousands various recipes, but still receive message - Waiting for all target devices to come online
I try to start Android studio as administrator, try to on/off various Window options (like enable/disable HyperV).
I try various options in device emulator, like wipe or cold start. But I have no changing. Device emulator not connected.
adb devices show me:
List of devices attached
emulator-5554 offline
In Android studio I see:
xx.xx * starting now at tcp:5037
xx.xx * daemon started successfully
And Launching I still see :
Waiting for all target devices to come online

What going wrong? Any ideas please..