LineNumbers and language highlight not working in merge view

v6
1 
new MergeView({
    revertControls: 'a-to-b',
    a: {
      doc: ACode,
      extensions: [
        lineNumbers(),
        basicSetup,
        language
      ],
    },
    b: {
      doc: BCode
      extensions: [
        lineNumbers(),
        basicSetup,
        language
      ],
    },
    gutter: true,
    parent: codemirror,
    highlightChanges: true,
  });

There is no line number nor syntax highlight in merge view, is it by design?
Thanks!

2

No. And I’m not seeing such a problem in the demo.

3

it works after upgraded to latest version.

Thanks!