Editing content with untranslatable fields in 2nd language on PlatformUI doesn't save changes

Steps to reproduce:

1. Ensure an ezpublish installation with three languages, eng-GB, fre-FR and ger-DE, for instance;

2. On legacy admin backend create a folder "Folder EN" in eng-GB language;

3. Edit it in fre-FR language and rename it to "Folder FR";

4. Edit it in ger-DE language and rename it ti "Folder DE";

5. Go to platformUI, to "Platform -> Content Structure";

6. Click on "Content tree" on the leftside menu, and on the content tree, click on "Folder EN";

7. On the language icon on the "Content" pane, pick fre-FR from the languages dropdown, then click on "Edit" on the action bar to the right;

8. Verify you're on the editing context for the fre-FR version of the content "Folder EN", which in such version is instead titled "Folder FR";

10. Rename it to "Folder FR v2" and publish it;

11. Take notice that the name editing has NOT been changed, it is still titled "Folder FR";

12. Repeat the same edition on "eng-GB" language editing context, by renaming it to "Folder EN v2"and publish it;

13. Take notice that the name ediuting has been changed as expected, it is now titled "Folder EN v2";