So here's the story:
I have a YouTube channel and the videos belong to me.
I take the embed code (iframe) and paste it into a WordPress post.
If I click Publish, it works, no problems.
But if I schedule it to be published at a later time - including one minute from now, as I just tested - the embed code disappears.
All other content of the post remains, but the whole iframe is gone.
I schedule a new video to be posted every Monday and have been doing so for over a year with no problems. The first time this happened was January 7. I can't be sure, but is that around the time the new version of WordPress came out?
Any ideas why this is happening?