Keynote presentation disappears after switching to YouTube app on iPad Pro

I have spent days working on some Keynote presentations on my iPad Pro. I was finishing up a presentation today and it disappeared when I reopened Keynote. I had switched to the YouTube app to grab a link for a video and my presentation was gone. No longer in the "Recents" folder, not in the "Recently Deleted" folder... Gone.

[Re-Titled by Moderator]