Export via API of Exception List returns {}

Hello there,

I'm trying to export an exception list via the Kibana API according to Export exception list.
I'm testing with Console at Dev Tools:
POST kbn:/api/exception_lists/_export?id=81039bc7-8b28-4435-8976-77a41d127c8d&list_id=eccde6e4-97ee-47ed-b8bb-aae97cc2229e
as well as with Python Requests.

Yes, I checked if the id and list_id are correct, took those from
GET kbn:/api/exception_lists/_find.

Using
GET kbn:/api/exception_lists/items/_find?list_id=eccde6e4-97ee-47ed-b8bb-aae97cc2229e
I'm getting one entry back.

When exporting it via UI it is working, but I need to use the API.

Am I doing something wrong or could someone verify on their instance?

Best Regards
Aaron