Microsoft Word Merge Fields display as the Tokens on a Vault Rendition.
If a Token's Field does not exist in Vault, then Tokens are not merged on the Viewable Rendition.
Check the Source Document for Tokens and be sure the all of the Fields exist as named in Vault. Also, the names should have the correct suffix. For example __v, __vs, or __c.
- Remove or correct the affected field from the Source Document.
- Upload the Document.
- Re-render the Document.
Vault Rendition Documentation: Merge Fields