Item group labels are not displayed when using 'allowed'

[minapok]

I use EXT:content_defender 3.4.1 in a TYPO3 CMS 12.4.7, PHP 8.1.

If I restrict the allowed content elements in a backend layout via 'allowed', the itemGroups labels aren't displayed in the "CType" selection field inside a content element. When using 'disallowed' the labels are displayed.

Example configuration:

mod {
     web_layout {
         BackendLayouts {
             example {
                 title = Example backend layout
                 config {
                     backend_layout {
                         colCount = 1
                         rowCount = 1
                         rows {
                             1 {
                                 columns {
                                     1 {
                                         name = Example column
                                         colPos = 0
                                         allowed {
                                             CType = text, shortcut
                                         }
                                     }
                                 }
                             }
                         }
                     }
                 }
             }
         }
     }
}

Is it possible that the item group labels are displayed while using 'allowed'?