Have you checked the duplicates, or email addresses - many times it happens that email addresses have missing "." or .com is not correctly spelled.
Also, check the import report, it will give the information why few leads are missing.
Here is where you need to click once you click on the static list - to check the list import status.
Once you click here, you will get a warning or message like what is given in the below snapshot. If the import was successful, it will give you a green check (Snapshot below)
If not successful then it will give you a warning. In your case it should say - "Warning - 1 people". Click-on the warning and a CSV file will be downloaded.
In the CSV one of the columns would mention the reason for import failure. You can then make the correction accordingly and re-upload the list.
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