This is old but I hope it helps others as I figured this out recently:
Any component that is attached to the camera is not going to trigger overlaps unless the player moves, so the workaround is to detach it from the camera component and, in the event graph, use a tick to set it’s world position to the camera’s location. It will then react to any overlap you want, even when the character is not moving. I’m using this to play an underwater sound when the camera gets inside water volumes and show water drops when it comes out.