Do you have a screenshot of the enrolled users page confirming you have more than 50 users. Could be the enrollment method be hidden ?
1. Current grader
2. Current users enrolled
I see quite a few user enrollment type 'dimmed' i.e hidden from showing up. Make sure you manual enrollment is enabled https://docs.moodle.org/33/en/Manual_enrolment#Editing_manual_enrolment_settings
Thank you for your response.
Attached is my enrollment configuration.
Just translated " hasta" into English it means untill.. doesn't that mean that the hidden student will only be enrolled till 30th September 2017.