TYPO3 Core

I've tried to use ExtensionManagementUtility::addTcaSelectItem() to register custom CType with item-group for CType Select. But obviously this argument is ignored and not passed to TYPO3 TCA:

  ExtensionManagementUtility::addTcaSelectItemGroup(
    'tt_content',
    'CType',
    'my-group',
    'LLL:EXT:my_slider_mixtape/Resources/Private/Language/locallang_tca.xlf:tt_content.group.sliders'
  );

  ExtensionManagementUtility::addTcaSelectItem(
   'tt_content',
   'CType',
   [
      // title
      'My custom CType',
      // plugin signature: extkey_identifier
      'custom_ctype'
      // icon identifier
      'custom-icon,
      // CType ItemGroup
      'my-group',
   ],
  );

Refering to the docs for this feature it should work like this:
https://docs.typo3.org/m/typo3/reference-tca/12.4/en-us/ColumnsConfig/Type/Select/Properties/ItemGroups.html