Locked Note Disappeared Before My Eyes

This morning I was reviewing an important note that I have locked and attached to my iCloud account. While I was looking at it it just disappeared and the screen went back to the list of notes. BUT this note was gone. I hadn't moved so did not touch the trash icon, but looked at the deleted notes folder and did not find it. I have looked on my Mac on my iCloud back ups and still missing...HELP! It's a very important note! I have researched the reliability and security of Apple Notes and this is why I kept this important info here!