Hello @witslk,
Make sure the course is set on drip feed mode. Edit the course, check the settings and make sure drip feed in enabled for the course.
Follow these settings:
Enabled unit start time access =>
https://prnt.sc/perpt7
Drip Feed enabled in course settings =>
https://prnt.sc/perr2q
Set Access Time and Access Date =>
https://prnt.sc/perqzj and enable these two settings from wp-admin -> lms -> settings :
Show unit slug and title in Course Status page
Enable Direct link to all units in curriculum(if student subscribed to course)
Thanks,