After adding new elements to IV you can no longer interact with the video in the editor.
h5p-overlay Is added over the video, and never removed.
The functionality that is lost after adding elements is for example the ability to click the video to play it, and hover over the big play button in the middle.
The issue is that h5p-overlay gets a h5p-visible class that isn't removed when done adding elements, it seems to fix itself if you navigate by clicking anywhere on the timeline at the bottom.
Make IV interactable again after adding elements