A Microsoft file hosting and synchronization service.
Hello Mr.Blue.1!
I understand that you're having trouble viewing thumbnails in your Personal Vault. This is actually a security feature designed to protect your sensitive files from being viewed by unauthorized users. Unfortunately, there is no way to deactivate this feature. However, you can still view your files in list view or by opening them individually.
I know this wasn't the outcome you'd expect, so please provide your experience as feedback to our developers. They'd love to hear from you about what's working well, what's not, and any ideas for improvements, including possible new features and functions. Your contribution will help us improve the user experience for you and all users around the world.
guide feedback: Send OneDrive Feedback - Microsoft Support
I hope this helps! Let me know if you have any other questions.
Regards,
Prince R
Microsoft Moderator