Session Sales Navigator and Recruiter import cards are retired. There is no sender tick that brings them back.
Open Contacts → Add contacts and choose People database or CSV import. For firms, open Companies → Add companies and choose Company database or CSV. Add manually when you have one record.
A LinkedIn URL on a CSV column or a manual record is identity for that person or company. It is not a pasted search scrape. Settings → Imports still shows old session jobs as history. Those rows do not offer Retry.