List numbering messed up after sorting

I'm experiencing an issue when sorting my personal lists on IMDb. All the films in my list are numbered according to the original order (from 0 to 100). However, when I change the sorting order (e.g., by release year or number of votes), the films are rearranged correctly, but their numbering remains the same as in the original (list) order. This means that the numbers do not update to reflect the new order (0 to 100) and they are completely mixed, therefore the list does not start at 0 and end at 100 as it should according to the new sorting.

Is this a bug or a new feature (in this case it is annoying one)?