It just happened to me, I have been using EN since 2009, it has never happened before. I am using Windows 10 Pro / Evernote 10.59.5 (updated yesterday)
My hours of work just disappeared, not found in history, I was using a regular note the same than ones I have been using for the last 14 years, I switched note, and when I get back I found an early stage of the note
The bad thing is the Trust Issues that comes after something like this, I am very concerned right now