Create User Task failed to be submitted due to looping PX Policy.
Here, the Create User Task was 'unsubmitted' status and see "[PROD]PX ##### - Check BaseEmail for Special Characters [Create]" PX Policy was looping.
Xpress policy is looping. There may be a logic issue in the way you've developed the PX; it could be due to a timing issue in the way that your policy is fetching or updating data from an LDAP, for example.
Remove the looping PX policy, restore to previously working PX Policy.
Rework the logic of your PX so that looping does not occur.