What might cause a change in a page design when importing it (in a module) from Commons?
I created a module, then shared it to Commons, then imported it into another course. A page showed up incorrectly in the new course. I peeked at it in Edit mode, and noticed that the HTML was changed from the original. I don't know if that happened during the export to Commons or during the import from Commons, but I went back and made small changes to the original, updated the Commons resource, and then applied the update to the new course. I did this multiple times and still the little code change that causes the pages to appear incorrectly.
Specifically, the change involves the deletion of "</iframe>".
The page includes a video clip with its text inside a box (technically, a 1x1 table) with material above it and below it. In the imported version, the material above the box appears, then the box shows the video without the text, and the page ends. None of the material below the box appears.
The original HTML designates the video-and-text box with the following code (none of which I really understand):
<table style="border-collapse: collapse; width: 100%;" border="1"> <tbody> <tr> <td style="width: 100%;"> <div> <iframe style="width: 400px; height: 225px; display: inline-block;" title="Video player for Video Title.mp4" data-media-type="video" src="https://canvasorganization.com/media_objects_iframe/m-4aY738e2f8t1wicsAPqLaoFm8VheUuoH?type=video" allowfullscreen="allowfullscreen" allow="fullscreen" data-media-id="m-4aY738e2f8t1wicsAPqLaoFm8VheUuoH"></iframe> <br /> <span style="font-size: 10pt;">Video text blah blah ...
See that </iframe> at the end of the sixth line of code? It's not in the code of the imported page. And that's the page stops in Read mode. (The HTML appears to have everything else.)