I don't have a Salesforce account available right now but will investigate this further as soon as I can.
In the meantime, can you try matching the following "structure" (for example in this example both camapign and CRM fields are defined for the remote key and modification date. Make sure that the remote fields are correctly defined compared to how they are named in salesforce.
This field is coming from the expression and I am not entering it manually.So, it seems if its been used once, then after that the system is taking only the field name and not the schema and therefore its ID_18_Digit_Format__c and not [Contact/ID_18_Digit_Format__c].
@id is my auto generated Adobe Primary key and ID_18_Digit_Format__c is the unique key. Both are different.
I am not very confident on mapping these as my requirement is to update 2 fields on SF based on the ID_18_Digit_Format__c field present.
Could not even find any document which describes these.