Why am I unable to see a lookup field that is newly added in Salesforce?
Scenario:
The Salesforce Admin created some new fields in an object, but a lookup field is still not showing in the Salesforce Source or Destination component.
Solution:
It may be that your Salesforce Admin created the field but did not properly set field-level security.
Your Salesforce administrator should make that field accessible for reading and edit and then the field should show up for you. Please contact your Salesforce administrator about the issue.
See the following supporting documentation links: