Mail drop not working?

I made a movie on iMovie on my iPhone. I have done this several times, and exported the video to my iCloud email using mail drop in order to be able to transfer the videos to my PC.

Today, when attempting to do the same thing, I can’t. I have tried several times over. In iMovie I get no error message, the app behaves as though the email and mail drop attachment has been sent. But my iCloud has no new messages. I waited ages and sent other attachments without mail drop, and those all went through. So it seems mail drop is the issue.

Problem is, my video file (47.5MB) is too big to send as a regular attachment. Any idea how to fix mail drop, or another way to get an iMovie video from iPhone to PC?