[Neos] New ContentCollection not shown on existing pages

[Maxi milian]

If I add to a template a new ContentCollection it is not shown on pages which are created before.

Config without new ContentCollection:
'TYPO3.Neos.NodeTypes:Page':
  childNodes:
    'teaser':
      type: 'TYPO3.Neos:ContentCollection'

Add „subcontent" to NodeTypes.yaml as new ContentCollection:
'TYPO3.Neos.NodeTypes:Page':
  childNodes:
    'teaser':
      type: 'TYPO3.Neos:ContentCollection'
    'subcontent':
      type: 'TYPO3.Neos:ContentCollection'

Afterwards I updated "Root.ts2" and „HTML-Template".

If I add a new page on the pagetree there are both ContentCollections „teaser" and „subcontent" available. 
But on existing pages there is just ContentCollection „teaser" available.

Cache clearing  or removing whole temporary/ directory does not solve the problem:
$ ./flow flow:cache:flush --force
$ rm -rf Data/Temporary/*

If I change the type of a existing page to 'shortcut' and afterwards to 'page' again both ContentCollections are available. But this couldn't be the right solution!?