Reviewers don't see the "Replace original with working copy" menu item in their actions in a folder that has "Intranet" Workflow. They do see it outside that folder and managers see it inside, too.
Which permission could this be? Could it be a permission? What else could cause this?
Any help is welcome!
You've to check if start role for the transition "Replace original with working copy" (you see the transition name in the link, when you can see it) is in the intranet workflow. Otherwise you've to add it in portal_workflow.
While there is often a wrinkle with this that may require some customization to the way this is done in any integration with any specific workflow or role mapping, I think you likely want to drop a pdb breakpoint() inside plone.app.iterate.browser.control.Control.checkin_allowed() method — this method is the primary gatekeeper on the action presence/absence for Actions > Checkin in the menu.