Preconditions:

• Added tag e.g testTag under Root tag in Content / Tags
• Added Content Folder e.g testFolder under Ibexa DXP content

Steps to reproduce

1. Log in to back office.
2. Go to Content / Tags.
3. Select tag 'testTag' from preconditions.
4. Switch tab to 'Content'. 
5. Click on 'Assign' button and in UDW assign tag to testFolder from preconditions.
6. Publish.

Actual result:

User can assign a tag to content which does not contains ibexa_taxonomy_entry_assignment field type.

Expected result:

User cannot assign a tag to content which does not contains ibexa_taxonomy_entry_assignment field type.