Can a file disappear from an ext4 partition if an application was using it?

A Passwords file was in use by KeePassXC. After restart, file is gone. Normal operation is: File is open and when system gets rebooted, it closes it safely (so far). Keepassxc always always autosaves. I've rarely seen "Save" available from the menu. Could KeePass have mishandled the file so badly that it just disappears?? Is there some other possibility? KeePass never screwed up a file before now.