Apologies for the double post. I have Windows 10, and I believe it happened after I let my computer go into sleep mode for a little bit. Unconfirmed of course, but it was fine not long ago, then suddenly just gone, while it was mounted I believe. :o I will be happy to provide additional information if you need it. As always, thanks for this useful software, and also your support.
The problem is there's no reproducible test case. It may work for months and never get corrupted. Third-party utilities like CCleaner and TuneUp are also known to damage image files, so it's also unclear which software to blame.
I had to stop using the persist to disk feature after I noticed data kept going missing. It's fine now on the normal hard disk. I understand it must be hard to find such issues. If you would like any help tracking these bugs down, let me know. Thanks again.