Question:
Why does the default role not get populated when using Lifecycle API for person import?
Answer:
This is a limitation of the Lifecycle API. All roles needed by the user account should be specified in the XML import, as none will be added automatically. You should also note that any roles for an existing user account will be overwritten, not appended to.
When adding the user through the client user interface, the default role is added automatically and synchronisation of the user account adds the role.