I'm working on a displacement map to display details from a high-poly mesh on a low-poly mesh. However, when I bake my displacement map, it appears almost completely grey.
What's causing this? Is there a way to fix it?
You are trying to bake a Displacement Map, but looking in your file shows you have no displaced mesh. What you want to do is create a Height Map from existing geometry.
This is a solution if someone experiences the same problem but has a displaced mesh: Check if you have applied the Displace Modifier and set Level Viewport to 0 in the Multires Modifier before baking the displacement.