We are running into a situation where certain prospects captured with Pardot forms are not syncing over to Salesforce because of a data mismatch. The problem is usually because what they enter in the phone number field doesn't match with the format for that field in Salesforce (ex: they include their extension with "ext."). Since Pardot requires the data format for a phone number to be "text" in order for someone to enter "123-456-7890", that leaves that field open to have anything input.