Why not simple embed script from Visme
<iframe src="//my.visme.co/embed/mxnnp0q8-linkedin-announcement" height="425" width="1400" style="border: 0px;" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe><p style="font-family: Arial; font-size: 10px; color: #333333">
I have just reposted this concern here as I am seeing similar case and use of <iframe>.
A user of our forum site tried to embed a 360 street view with the following code, shows up on the rich text editor with no issues but does not appear on the post after submission:
<iframe src="https://www.google.com/maps/embed?pb=!1m0!4v1507725217680!6m8!1m7!1s0pDgVCL2f7fqIKQTKSyDAA!2m2!1d9.317219321713546!2d123.3039477515308!3f282.23!4f-3.9399999999999977!5f1.1924812503605782" width="600" height="450" frameborder="0" style="border:0" allowfullscreen></iframe>
Forum URL: Negros Chronicle Forum
Post with issue: Traffic Management Office Concerns
Please see the following snapshot. Notice the embedded street view appears on rich text editor and only the code shows up on submitted post.
As a workaround, for the meantime, I've told the user to just put a link to the 360 street view and just post snapshots as overview of the situation.
We have tried to put it on "source", didn't work.