Hi there,
The number of learners on a course detail page is part of the Sensei Course Participants plugin.
This plugin has now been retired and is no longer maintained. Because of this, we are limited in the support that we can provide for the plugin.
https://senseilms.com/2021/07/29/retiring-two-sensei-lms-extensions/
—
The Course Participants plugin only shows active learners who are enrolled in the course. It will not show the number of learners who have completed the course.
You can check the number of Active learners on the course from WordPress Admin > Sensei Lms > Learner Management > Course Name page. On this page check how many learners have in In Progress or Not Started status.
If the total number of learners in the In Progress or Not Started status does not match with the number shown on the course detail page, please try clearing any caches you may have on the website and check again.
Thanks!