Drag and drop/available/locked not working in nested catalog view

Description / Beschreibung

The drag and drop functionality in management/catalogs/<catalogId>/nested/ is not working.
Dragging is possible, but nothing is saved and after a reload of the page the change does not persist.
The network error when dragging is:

URL: http://localhost:8001/api/v1/questions/questionsets/108/
Status: 400 Bad Request
Quelle: Netzwerk
Adresse: 127.0.0.1:8001

Anfrage
PUT /api/v1/questions/questionsets/108/ HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Accept-Language: de-DE,de;q=0.9
Cache-Control: no-cache
Connection: keep-alive
Content-Length: 3169
Content-Type: application/json
Cookie: csrftoken=4BeWfcUZ5PECf0QI8R0Kz0R1sOoUZRAV; storeid=46bb5ff6d66889c3167d3e984c57e04d427bb5142b7ce22f643ec07c535f3d5c; sessionid=fpzoycp66qfimzo91c4lrm9l31563wjk; django_language=en
Origin: http://localhost:8001
Pragma: no-cache
Priority: u=3, i
Referer: http://localhost:8001/management/catalogs/5/nested/
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.5 Safari/605.1.15
X-CSRFToken: 4BeWfcUZ5PECf0QI8R0Kz0R1sOoUZRAV

Antwort
HTTP/1.1 400 Bad Request
Allow: GET, PUT, PATCH, DELETE, HEAD, OPTIONS
Content-Language: en
Content-Length: 81
Content-Type: application/json
Cross-Origin-Opener-Policy: same-origin
Date: Fri, 24 Jul 2026 09:06:54 GMT
Referrer-Policy: same-origin
Server: WSGIServer/0.2 CPython/3.13.3
Vary: Accept, Accept-Language, Cookie
X-Content-Type-Options: nosniff
X-Frame-Options: DENY

Expected behaviour / Erwartetes Verhalten

Drag and drop changes should be saved.

Steps to reproduce / Schritte zum Reproduzieren

1. Go to a nested catalog view (management/catalogs/<catalogId>/nested/)
2. Click on a drag and drop icon and move the element
3. See eventually "This field is required." in the UI and a 400 Bad request error in the dev tools network tab.
4. Reload the page
5. See the change was not made

Context / Kontext

RDMO 2.5.1

References / Verweise

original Issue was: #1678 (split into different issues)