I am actualy trying to get the results of a massive Slide scan action into Lightroom and experienced that the file name processor is instable, and may even cause LR to crash.
In LR behind the file name is an icon by which the file names of the pictures can be processed or barch-changed.
In my case it often appeared that the numbering was skipping number of slides that had been destroyed.
When using the batch file name change function the change of part of a serie to a higher number (and thus overwriting the similar numbers in the series) does end up in a library view where some slides may seem duplicated, and others have dissapeared.
When clicking on the slides in edit mode may result in another slide being shown, but when going bach to the library view this can be retained, but often it is just going back to the wrong view.
However, when going to the edit view, LR may also crash.
When it occurs a LR restart may help to restore the view and numbering, but also that may not to happen.
A BUG to be fixed in my view.