If the employee swipes are not reflecting on greytHR one of the reason could be the "employee Access Card numbers are duplicated".
You can run a report on greytHR to get the access card numbers for your employees by navigating to the Reports section.
Watch the video to know more about report generation on greytHR.
Once the report is generated you can find employees with duplicate employee numbers and correct the same by navigating the employee Access Card Section.