Impersonation in plug-ins is not supported while in offline mode.

What is impersonation in plugin?

Impersonation is used to execute business logic (custom code) on behalf of a Dynamics 365 Customer Engagement (on-premises) system user to provide a desired feature or service for that user.

What is impersonation in MS CRM?

Impersonation is used to execute business logic (code) on behalf of another Dynamics 365 for Customer Engagement user to provide a desired feature or service using the appropriate role and object-based security of that impersonated user. ... More information can be found in the Dataverse topic Impersonate another user.