When using the Atlassian-created Okta application, the values selected by default for the nameID for SAML uses the Okta username. The SCIM email setting uses the primary email by default.
Given that these values need to always match in order to function, I would like to suggest setting the defaults to always use the user email and not to use the Okta Username as the default for both.
If possible, I would also like to suggest a way to link the two values to be from the same attribute or set them independently if needed.