Mutation Observer childList is not detected

[deerawan]

Describe the bug
Mutation Observer childList is not detected on Storybook.

This is for index.html that specifies the component. See that mutations log exists

Below is Storybook, no mutations log displayed

To Reproduce
It's reproducible in this repo https://github.com/deerawan/mutation-observer-storybook

Important files:

• action-group.ts (link)
• index.html (link)
• action-group.stories.ts (link)

System

System:
    OS: macOS 12.1
    CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
  Binaries:
    Node: 14.17.0 - ~/.asdf/installs/nodejs/14.17.0/bin/node
    Yarn: 1.22.18 - ~/.asdf/installs/nodejs/14.17.0/.npm/bin/yarn
    npm: 6.14.13 - ~/.asdf/installs/nodejs/14.17.0/bin/npm
  Browsers:
    Chrome: 100.0.4896.127
    Firefox: 99.0.1
    Safari: 15.2
  npmPackages:
    @storybook/addon-actions: ^6.4.22 => 6.4.22 
    @storybook/addon-essentials: ^6.4.22 => 6.4.22 
    @storybook/addon-links: ^6.4.22 => 6.4.22 
    @storybook/web-components: ^6.4.22 => 6.4.22 

[snortblt]

Seeing this too

[shilman]

Is this still an issue on 7.0?

Migration guide: https://storybook.js.org/migration-guides/7.0

[ahuangServicenow]

I believe this is still the case for 7.0. I guess the mutationObserver basically cannot observe the element in iframe? is there a way we can disable the iframe in preview?