If I copy & paste paragraphs that have list numbers, I find that sometimes the pasted paragraph retains the original list number rather than being renumbered in sequence, and that paragraphs subsequent to the pasted paragraph then are renumbered sequentially. For example, if I insert a copy of paragraph 3 after paragraph 8, the inserted paragraph occasionally will retain its old number 3 rather than being renumbered as 8, and the following paragraphs will be numbered as 4, 5, 6, etc. The entire sequence then becomes 1, 2, 3, 4, 5, 6, 7, 3, 4, 5, ...
I have a feature suggestion that may solve this problem, which is why I'm reporting it here rather than reporting it to Nisus as a bug. In the List pane of the formatting drawer, add a checkbox for "Restart numbering at this paragraph". If the checkbox is not ticked, then grey out the fields for Number and Increment. Hopefully that will prevent the Number field from being replicated when a paragraph is pasted.
If anyone else shares this problem and concurs with my feature request, please submit a feature request via Help menu > Send Feedback.