Thank you for bringing this issue to our notice and we apologize for the inconvenience. The expression builder is not reading the source attributes (SuccessFactors fields in this case) associated with HR-provisioning app. We plan to work on fixing this issue and we will share an ETA as soon as we have more clarity on the dates. Meanwhile to test your expressions, we recommend using provision on demand capability. If you need help with a specific expression, please feel free to post it in the community here or reach out to our support team.
Thanks,
Chetan