No visible units in the course currently. Please check back later.

Even though all settings are correct and the admin account can see the course and units, whenever a student tries to access a course, they are given the message:

"No visible units in the course currently. Please check back later."

Full plugin and theme conflict test has been performed. No debug.log output. No JS Console output. Same results with PHP 7.2.x or 7.0.x. Fresh install of WordPress.