The timeline entries vanished when I clicked “Update”

I spent time styling the default timeline, and adding entries, and saving my work as I went. Everything was fine. The shortcode displayed the timeline on the page where I added it.

Then I clicked “Update” one more time and all of my work vanished, and the timeline vanished from the page it was entered on, and the plugin went back to its default, as though I’d never done the work. I lost a couple of hours of work, and I have to do everything over again, so instead of redoing my work using your plugin or paying to upgrade it (why??) I’m going to uninstall this plugin and find something more reliable to use.