TYPO3 Core

I created a couple of new CEs and some need to have "pages" enabled - so i tried the following:

'new_contentelement' => [
'showitem' => '
-- Palettes etc., no relevant data
',
'columnsOverrides' => [
'pages' => [
'exclude' => false, //not working for Usergroup...
'config' => [
'maxitems' => 5, //works like a charm
]
],
],
],

Then i cleared the cache, logged into the User which should edit the CE and i saw the pages field and could add/delete pages but after i saved the CE the element was empty.
Then i added some pages with the admin user - worked without problems -, logged in with the user which should edit the CE and he saw the new added pages but couldn't add/delete pages by himself.