Why the Tracking Data of emails sent from below journey are NOT synced and showed under Individual Email Results?
IS THIS SOMETHING TO DO WITH AS I HAVE TAKEN API AS ENTRY SOURCE!!
If you are sending Emails via Journey Builder, then it doesn't matter if your Data Extension is in Salesforce Data Extension folder or in the regular Data Extension folder, as long as you have the Send Tracking To Sale Cloud checked it will work.
If you are sending Emails via regular Send and your target is either Salesforce Campaign or a Salesforce Report, then the tracking will be sent to Sales Cloud, but if you target a regular Data Extension, then Tracking will not be sent to Sales Cloud.
User-Initiated-Send and Salesforce-Send are fortunately working in a clear way, and thus eliminating any doubts when sending emails through Automation Studio. Use Salesforce-Send for Salesforce Data Extensions / Reports / Campaigns to have the tracking sent to Sales Cloud.
Other than that, just make sure you are using either the 18-digit PersonContactID or LeadID as the Subscriber Key and have the Send Tracking to Sales Cloud always marked.