Using the Salesforce connector, some fields within objects are not able to be retrieved. For example, if we were to choose the object "Asset" you might lack fields such as OwnerId or ParentId. If permissions have been checked and the items can be viewed within Salesforce Workbench then adding the optional URL to the connector could help.
The Salesforce Connector Version 14.1 supports up to Salesforce API version 35. If the environment is running a newer version it will need to be specified in the URL to force use of the environments newer version.
The URL for the connector will need to reflect the current Salesforce API version. Check within Salesforce for the API version by going to Setup > App Setup > Develop > API.
After retrieving the version information you will add it to the end of the URL for the connection as follows. https://salesforce.com/services/Soap/u/39.0
Use all other fields that are needed within your environment to create the connection and then replace 39.0 in the URL with the version that's being run.
After testing the connection finish by choosing create. You can now try loading the objects in question and verify if the missing fields have been retrieved.