When a Content Type has an Image Asset field with the "can be a thumbnail" option checked, the thumbnail won't be displayed in the Backoffice when DAM image is used.

Steps to reproduce:
1. Clean installation of Ibexa DXP 3.2/3.3
2. Log in the backoffice as the admin user and create a new Media Content Type DAM Image with fields:

3. Setup Unsplash DAM bundle (please, check here)
4. In the /Media/Images/ create a new Content of the DAM Image type, for the Image field, select and Image provided by DAM. Publish it.
5. Go to /Media/Images/ and change the sub-items view to a grid.

Result:
Thumbnail is not displayed for newly created Content.

Expected result:
Thumbnail is displayed normally.