Steps to reproduce:

1. Clean installation of Ibexa DXP v3.3.
2. Edit Article Content Type and edit Image fieldtype, select all Content Types in Allowed Content Types.
3. Create a new Role and assign the following policies to it (including a new user):
   
4. Create new Article Content Type and during creation select a relation to an Image.

Result:
You cannot select any content type different than in Content/Create policy.

Expected result:
You should be able to select any Content or there should be a different validation mechanism.