TYPO3 Core

I think I've found a way to reproduce this issue on latest master (by the way: the code mentioned in the description is still present):

Prerequisites¶

1. TYPO3 with more than one language (e.g Italian (Default) and English (ID=1)
2. A page with more that one language

Test¶

1. On a page (that has a translation) create a category "TEST" (use List view)
2. Translate "TEST" in the other language (call it for example "TEST ENG")
3. in List view > Edit "TEST ENG" > go to "Languages" tab

- the dropdown Transl.Orig [l10n_parent] has two entries:

[0]
[x] TEST

where [x] is the ID of the "TEST" category

4. Select the empty entry ([0]), save and close
5. Edit again "TEST ENG"
6. Go to "Languages" tab and click on the Transl.Orig [l10n_parent] dropdown

Result:¶

The dropdown contains only the "[0]" entry, so it is not possible to reassign the category to the original "TEST"

Note¶

I don't know if this is "by design": in fact, what values should the dropdown show? It should be every category in the default language

Patch set 3 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/66221

Patch set 1 for branch 10.4 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/66293