Corrupt list

One of my private lists named "MyMovies:OK" includes the 3326 I have watched.

In display mode it looks ok but when I open the list in Edit mode I can see that the numbering has been corrupt.

Between number 2296 and number 3008 there are several with same number and some numbers is missing and from number 3009 to the end the number is one number short meaning that the last number is number 3325 even that the list contains of 3326 films. The same happens if I export the list to other media.

I realized this on Friday last week and have after that not done any changes in the list.

Could you please help, I would like to avoid creating a new list with all those films even if I have them all in an spreadsheet as well.