@Waindigo I have installed this addon but when I log in with an admin account to test it the addon doesn't ask me to complete the field I've marked as mandatory.
In the screenshot I also see you have custom fields on in but your addon doesn't have an option to mark custom fields as mandatories:
The sequenze I have tested
1) make a field like Facebook mandatory
2) run the cron Job
3) Login with a user, who has an empty Facebook field (everything is working like supposed - don`t enter a value and Log Off)
4) disable the "required" flag at Facebook in ACP
5) run the cron Job
6) Log in again --> you get the error shown to enter values for required fields which don`t exist (the Dialog is messed up).