Code autocompletion (emmet) not working on github codespace for HTML

Question

I am new to codespace and am not getting any code autocompletion for HTML. Checked emmet, it should work, but it's not. What could be the problem? I added this to settings.json and it's still not working

    "emmet.triggerExpansionOnTab": true,
    "emmet.includeLanguages": {
    "javascript": "javascriptreact",
    "vue-html": "html",
    "razor": "html",
    "plaintext": "jade",
    "javascript": "html"
    },