The setting page | printintro works when the display is set to "Open". But it does not work when display is set to "In pop-up.

REPLICATION

1. Go to the course page
2. Under any section, click “Add an activity or resource”, then click “Page”
3. Fill in these fields:

Name: (anything of your choosing), e.g “hello”
Description: “description”
Page content: “page content”
Set Appearance → Display to “In pop-up”
Set Appearance → “Display page description” to checked
4. Click “Save and return to course”
5. Click on the page resource you have just created

RESULT
The description does not appear in the pop up. However, if you choose Appearance / Display to Open, the Description is displayed correctly.