Hello @AliciaK95. I see that you did also email our Support team about this contacts question as well. As they suggested in the email reply to you, there may have been contacts in the files that you uploaded that only had names and did not have email addresses. A contact must have an email address in order for it to be added to a list. The contacts without email addresses would still show up under "View All Contacts" but they are not considered active and able to add to a list because we would not be able to send an email to them.
I hope this helps and answers your question.
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