Mac Mail strange behavior
Perhaps 2-3 times a week, Mail randomly moves a message from InBox to another mail box. This happens only after I've read the message. Typically, I discover it's gone when I need to refer back to it. Usually it turns up in the All Mail folder and I can move it back to the InBox. But until I find it, I panic, thinking the message has been deleted. I can find no reason for this. I've checked Rules and I've checked config settings, but can find nothing that would cause this. Fortunately, these messages don't show up in Trash folder, but still, it's seriously annoying. Ideas?
MacBook Pro 15″, macOS 10.13