So, we did the normal things...
- Made sure the field printed fine on the report writer report (it did)
- Removed and re-added the XML source to the Word template
- Removed and re-added the field to template
- Added static text to the template to make sure we were printing the right template (we were)
But then I remembered a blog post that I had read about making sure that fields were associated with the section that are printing in. When you are looking at the field pane, you will notice that fields are displayed based on the section (this is derived from the report writer report itself, so wherever the field is on the standard report- that is where it shows in the field pane).