Steps to reproduce:

1. Install Ibexa DXP v4.5.
2. Create two tags.
3. Create a new content type with the ibexa_taxonomy_entry_assignment field.
4. Create a second language.
5. Create content based on the created content type and set one tag.
6. Add a translation to the added content.
7. Try editing the content and adding another tag.

Result:

The content is not saved, and the changes to the tag field are lost.

Expected:

The content should be saved, and the changes to the tag field (add, remove) should be preserved.