Currently, date fields with null values are not sent through the MC connector. I'm not sure if this also applies to other types of fields.

This means that if a date field is populated in MC, then updated to a null value in RE, the date will not be overwritten in MC with the new value.

Because we use these date fields (expiration date, date joined, etc) as segmentation criteria, this affects our marketing campaigns to targeted audiences and can cause significant problems.