Migrating CRM 4.0 entity records to CRM Online using Kingswaysoft

I am trying to migrate Dynamics CRM 4.0 entity records to CRM Online using Kingswaysoft.

In a data flow task I have enabled a data viewer to verify the data coming through the 4.0 CRM instance (source). When I selected all columns and data without any filter on the source component, it showed only around 200 account entity records out of around 4036.

To narrow down which columns might be causing this issue, in the source component, I just selected few of the columns from the top sorted alphabetically.

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Up to the address1_country fields selected in the list above, all the 4036 records are being returned. When I selected the address1_county field it returned 3983 records (53 records were missing).

To further analyze what's happening around this field I just configured the source to return accountid and address1_county columns in the source component, that surprisingly returned all 4036 records (no records were missing). Also note, that address1_county field has value in none of the 4036 records. It has not been used at all.

I am facing this issue with few other fields also that have important piece of data and unable to figure out what's the reason behind this?

Please help.