Using the Lightroom Album API to list the assets of an album I have found that for some albums the order in the album is not returned accurately. For example if the order of items in the album are shown to be ABCDE, then the API might return the items as ABCED. To fix this, I found that reordering the items in some way in Lightroom and then moving them back fixes it in the API results.
This is the API I am working with using the parameter order_after=-
https://www.adobe.io/apis/creativecloud/lightroom/apidocs.html#/albums/listAssetsOfAlbum