2019-09 B のパッチに既知の問題（日本語環境関連）？

Windows 10 ver 1709~1903 の 2019-09 B 更新に以下の既知の問題が追加されています。

"Unable to create local users in Chinese, Japanese and Korean during device setup
You might be unable to create users in Chinese, Japanese and Korean using Input Method Editor (IME) during OOBE."

詳細

"Unable to create local users in Chinese, Japanese and Korean during device setup
When setting up a new Windows device using the Out of Box Experience (OOBE), you might be unable to create a local user when using Input Method Editor (IME). This issue might affect you if you are using the IME for Chinese, Japanese, or Korean languages.

Note This issue does not affect using a Microsoft Account during OOBE.

Affected platforms:

    Client: Windows 10, version 1903; Windows 10, version 1809; Windows 10 Enterprise LTSC 2019; Windows 10, version 1803; Windows 10, version 1709
    Server: Windows Server, version 1903; Windows Server, version 1809; Windows Server 2019; Windows Server, version 1803; Windows Server, version 1709

Workaround: To mitigate this issue, set the keyboard language to English during user creation or use a Microsoft Account to complete OOBE. You can set the keyboard language back to your preferred language after user creation. Once the OOBE is done and you are at the desktop, you can rename the current user using these instructions. If you prefer to create a new local user, see KB4026923.

Next steps: We are working on a resolution and estimate a solution will be available in late November."

けど、2019-10 B 適用済みの Windows 10 ver 1903（18362.418） Sysprep 済イメージがあったんで、試してみてもこの問題を確認できず。日本語のローカルユーザー名で問題なくセットアップできちゃった。

どういう問題なのかよくわからない。