EPUB Interactivity Preview & Media panels not working correctly (ID 16.3.2, macOS 11.4.1)

[Inélsòre]

I am studying lesson 15 of the Adobe InDesign Classroom in a Book, covering animations and interactive EPUBs.
The EPUB Interactivity preview panel needs to be closed (Ctrl-click > close panel) and reopened to correctly preview animations. It will be unresponsive instead.
The Media panel opens with a light grey background inside. It is unusable.
Here is the link to a video showing the issue.

https://www.dropbox.com/s/7d2oc0yjgjvwkp0/EPUB%20-%20Media%20panels%20bug.mov?dl=0

Attached also the file of the lesson. 

[Frans v.d. Geest]

(Edited. Sorry, misread), Did you try the good old delete settings at start up option?

[Inélsòre]

Not yet.
Could you remind me how to do that?
Does it reset all my global InDesign Preferences?
Just to be sure: are these panels behaving correctly on your system?

[Srishti Bali · Accepted solution]

Hi there,

Sorry about this trouble. Please try following these steps one by one and let us know how it goes: 

• Rename CEP folder to CEP.old from /Library/Application Support/Adobe   
  

• If that doesn't help, rename extensions to extensions.old folder from  /Library/Application Support/Adobe/UXP 

While performing each step, please make sure that all Adobe apps are closed.  Feel free to let us know if you still need assistance. We'd be happy to help. 

Regards,

Srishti

[Inélsòre]

Thank you so much, Srishti!

This solved it! Both panels are now working correctly!