Can not debug at nRF Connect for VS Code v2.5.2 and v2.6.0

[agishii]

Hello,

I'm doing the tutorial video of nRF Connect for VS Code part5:Debugging.

https://www.youtube.com/watch?v=IDC2m91xMb0&list=PLx_tBuQ_KSqEt7NK-H7Lu78lT2OijwIMl&index=5

I use nRF9160DK board, blinky_pwn froject.

The video shows there is a checkbox "Enable debug options".

but, my environment has no like that check box as below.

I can run the program but I can not debug it.

The video also shows how to ebabe the debug by prj.conf and I set it, but still can not debug.

I read the manual on web, 

https://nrfconnect.github.io/vscode-nrf-connect/get_started/quick_debug.html

This say that I have to set "Optimize for debugging". And I did, but no change.

I could not find the newest manual for v2.5.2 or v2.6.0. Where shold I see?

[agishii]

I reconnect the SDK board, mean turn off the board once, I could debug it.

I have no idea why it could not debug before.. but now is OK.