Trying to bake displacement but it keeps baking this solid black and white texture over the sculpted areas. I’ve tried everything and can’t see any fixes. Anyone has an idea on what is causing the problem?

In multires modifier, there’s should be an option called Apply Base. Try to click on it. Maybe it will help you.
Cheers,
Sergey
There was something about selecting the correct subdiv level to bake from (or to…?? viewport vs render settings) and/or enableing Low Resolution Mesh (calcualte height against unsubdiv low res mesh)…
It’s still the same. Apply Base is something I’d prefer not to do as it’ll change the mesh.
I’ve done everything. This isn’t the first time I’ve baked displacements but this project just doesn’t bake properly.
I’m also baking into a UDIM texture which is probably the cause because whenever I bake displacement on a single texture, it works properly. I have the latest Blender version so I’m sure that UDIM baking is supported.
I am getting the exact same issue. If I have UDIM I get black and white texture. If I remove UDIM it bakes fine. I also tried opening the file in 3.5.1 but still got the same issue.
The way it “worked” for me for now was using a UDIM baker add-on that I downloaded way back when Blender still didn’t support UDIM baking. Unfortunately, I don’t remember where I got it.