If a swimmer is not appearing in the Not Committed tab when trying to commit them to an event, ensure that both the Account/Member Account's status are Active.
Go to Org or Team Tools > Accounts and search by the last name.
Check to ensure the Account Status is Active.
If not, click the name and scroll to Account Access Settings. From Account Status, choose Active > Save.
If the account is active, click the account and click the Members tab to check if the Member is Active. If the member is not active, under the Member Status drop-down, choose Active > Save.