When the Business Central to Dataverse integration is configured, one of the tables installed in Dataverse is the Company table (bcbi_Company). When the Company lookup is added to the Dynamics 365 forms, the display value of the lookup field is shown as a GUID and does not show the Company name. This is because the Primary column of the Company table (bcbi_Company) is the 'External Id' field (bcbi_ExternalId) which contains a GUID value.

This behavior is not user friendly and ideally the Primary column should be the Company Name.