Employee not able to continue on the next Activity and shows locked

Summary: We have setup a course - offering setup, where the offering contains multiple activities. All the activities are setup in the default section and second activity onwards the sequencing rule is setup as "After completing prior activity".

All activities have the option to complete the activity by marking as complete.

Now when an employee is enrolled into this offering, they are able to open the first activity and "Mark as Complete" option appears they are able to do the same. Now while the second activity sequencing rule(Learner Can Access Activity) is setup After completing prior activity, still the "Mark as Complete" option not available on second activity and it shows locked.