I have problems with the v4 endpoint for updating the contents of a list (https://api.themoviedb.org/4/list/{list_id}/items). Sometimes it updates and sometimes it does not, but even though the list does not get updated, i get a success answer from the api. Here are 2 videos of what i mean.

List updating correctly: https://www.youtube.com/watch?v=7FTSMc0DSxo List not updating: https://www.youtube.com/watch?v=P5lruKWLIZM