Unexpected behavior while deploying to custom branch

[sceptic30]

Im facing an unexpected behavior while deploying with the command:
mike deploy -b v4.0 -m v4.0_MikeDeployment v4.0

I see that the site directory is populated with hmtl files and folders, but there is no versioned folder, no version.json, no index.html.
When I execute git status I see that the said wanted folder (v4.0) has been deleted along with all the other related files that Mike normally produces.

Is there any workaround for this problem? is this the expected behavior?
If I remove the branch switch -b, then Mike automatically creates a gh-pages branch, where I can see the v4.0 folder along with all the Mike related files.
Why is this happening?

My mkdocs (Mike) config is:

plugins:
  - search
  - mike:
      alias_type: copy
      redirect_template: null
      deploy_prefix: ''
      canonical_version: latest
      version_selector: true
      css_dir: stylesheets
      javascript_dir: javascripts

[jimporter]

The behavior you describe is the expected behavior. The site directory is just the temporary build folder that mkdocs uses to generate the docs, and so it's not set up for versioning (that happens later when mike generates your Git commit).

In your command, you're requesting that mike deploy your generated docs to your v4.0 branch, so if you check out that branch, you should see your versions.json file and versioned docs. However, that might not be what you want; do you really intend to commit your generated docs to the v4.0 branch? Generally, you'd want them to live in some common branch that all versions can share (otherwise, there's not a lot of value to the multi-version support from mike).