Instructor role users don't show as options for Course Authors

Reproduction Steps

• head to a site with LifterLMS (a site that has at least 1 admin and 1 instructor)
• /wp-admin
• head to Courses
• Bulk Edit one of your courses
• Head to try and change the 'Author'
• The Instructor users don't appear in that dropdown to change the author of the course to an 'Instructor' user
• Only admins appear in the dropdown

https://www.loom.com/share/c21b60fee3d6471196f33b458344d031

(Current workaround, make your instructor an admin temporarily to have them appear in the dropdown)

Expected Behavior

We'd see both admins and instructors, the roles who have permissions to author courses

• Include a concise description of what you expected to happen (but didn't)

Actual Behavior

We don't see instructors, only admins

• Include a concise description of what actually happens (but isn't supposed to)

This issue has be recreated:

• Locally
• [ x] On a staging site
• [ x] On a production website
• [x ] With only LifterLMS and a default theme

Will & Chris ran into this issue while creating Chris's demo site. I've seen this issue before, but I tell people to use the workaround of temporarily making their instructor an admin to resolve it.

Start in the WordPress Courses bulk-edit flow and inspect how the Author dropdown filters users by role. Done means users with the Instructor role appear alongside administrators, and the staging reproduction no longer shows the reported behavior.