Question:

Why a user does not have permission to view the Narrative Preview, Company Comments and Reporter's Comments fields on the Case record?

Answer:

The user must have View permission to:

• Narrative Preview, Company Comments and Reporter's Comments Object Controls using a permission set and Atomic Security
• the Localized Case object record
• the Localized Narrative document

in order to be able to see the content of these fields.

Related Documentation:

Vault Help Documentation: 

• Prepare a Domestic Case
• Compose a Case Narrative