Just came across the same problem in a drawing. I can swap the part from a 525mm to 450mm, but only the description is updated. All the other info remains 525mm. I've audited the drawing as well, but the problem still exists. There's a few sizes in the drawing that are that way. Using C3d 2009. I've been searching online and haven't found any solutions for this.
Hi Travis-
I have come across similar issues in the past, and typically it is caused by some sort of drawing corruption. What happens if you LANDXMLOUT the pipe network and LANDXMLIN into a new clean drawing? Can you then swap parts without issue?
This problem still exists in Civil 3D 2011 when using my 2008 drawings. Funny thing is this problem isn't showing up when I open those drawings in Civil 3D 2009.
Michaela
When I have seen this issue, it typically effects only one or two specific sizes. I have used these steps to get the desired result and swap in for the correct part:
Hope these steps can help overcome this issue!