be (right) under (one's) (very) nose

1. To exist or be located in a place that is very easy to locate or plain to see. I've been looking all over for that invitation, and it was under my very nose the whole time! Don't worry, the kids will be right under our noses the whole time, so they won't be getting into any trouble while you're gone. Mom, I found your glasses! They were right under our noses this whole time.

2. To be plainly evident or easy to identify. Upper management keeps saying they don't know how to solve the problem, but if they would just look at the data we're providing them, they would see that the solution is right under their very noses. A: "Are you telling me that the culprit has been under my nose this entire time?" B: "Yes, it is, in fact, one of your students." The issue is right under your nose, bro—your car is low on oil.