some contents are missing through iframe embed

Hello.

I'm using my h5p contents created in  wordpress under the subdomain. I'm embedding all of my contents in the posts of my main domain. in this post you can see that all the contents are appearing except the last one which is a "course presentation content". all of them are embedded by using iframe from the same subdomain. I don't know what's wrong with it. can anyone give some ideas what to do ?

https://classtop.ir/%d9%84%d8%ba%d8%a7%d8%aa-%d9%be%d8%a7%db%8c%d9%87-%d...

I put the same content in a post in the subdomain using H5p shortcode and it worked. it only prevents to show up in iframe.