Tab does not tab and lets me out the code

I am working with ipynb file on Visual Studio Code. (with Github Copilot)

I thought it would provide tab or Copilot autocomplete when I press Tab key in a code block.

But it didn't, and let me out the code block - just like when I'm using Tab in a webpage.

I checked the Keyboard Shortcuts settings, but what I got were only the followings:

Emmet: Expand Abbreviation
accptSelectedSuggestion
editor.action.inlineSuggest.commit
insertBestCompletion
insertNextSuggestion
insertSnippet
jumpToNextSnippetPlaceholder
tab

I don't have any idea to fix this problem. How can I prevent Tab from popping me out of the codeblock?