I am trying to change the approval status on a workflow to rejected, but it is staying as pending approval. When I look at the workflow logs, they say that the approval status is being changed to rejected, but the record is not changing. Does anyone have any ideas of why?

This was what I got from NS - same issue: The ability to set the Document Status to Rejected is currently an Enhancement Request #176673. This feature has been requested by several customers, however there is no current target release date. An alternative suggested in another case is to create a custom Approval Status field and have that field be updated by the workflow.