TYPO3 Core

When you have an extension, which includes TypoScript (settings) for a plugin and a backend module, the TypoScript typically consists of a plugin.tx_myextension part for the plugin and a module.tx_extbaseupload part for the backend module.

Example:

plugin.tx_myextension {
  settings {
    foo = bar
  }
}

module.tx_myextension {
  settings < plugin.tx_myextension.settings
}

When the TypoScript of an extension is added via the TypoScript template, both the frontend plugin and the backend module can access configured TypoScript settings. When using extbase, this is usually done by accessing $this->settings in a controller.

When the TypoScript of an extension is added via a site set, only the frontend plugin can access the TypoScript. For the backend module, $this->settings is an empty array.

It seems, that BackendConfigurationManager is not aware of the site set TypoScript include and does not resolve it in getTypoScriptSetup().