Hi ook,
For the DF Resolution, make sure that you’re adjusting the Distance Field Resolution Scale and NOT the Distance Field Bias. If the DF Bias is adjusted higher the mesh will either not render or render less of the mesh.
If that’s not the issue you’re seeing, make sure that you’ve got the Engine Scalability set to EPIC or HIGH for DF Shadowing. Screenshots would likely be helpful as well for the Mesh Distance Field visualization with the various DF Resolutions that work (Show > Visualize > Mesh Distance Fields).
CSM and DFAO are not mutually exclusive. You can use these together because not everyone will want to use DF Shadowing for their directional light, but they may want DFAO from their movable skylight. one quick way to check is by adjusting the Occlusion Tint to an obvious color and you can see the areas that are getting occlusion more easily.
-Tim