The visual appearance of the displacement map itself (like the black patches you mentioned) does not necessarily indicate a problem with the map. The EXR files are high-quality 32-bit floating point maps designed to provide accurate displacement data without needing adjustments for scale and bias—just set the scale to 1 and the bias to 0. The jpg version is a normalized 0-255 map with scale and bias values that are specified in the json for each asset. Each asset will have its own unique scale & bias values when using the jpg displacement map as a source
While the visual representation may differ, the functionality of the EXR maps is not affected. They are intended to deliver better results in terms of displacement quality when applied to the mesh. The differences you’re seeing could be due to improvements in the asset generation process in the new system, which aims to enhance the overall quality and performance of the assets.
Here is a comparison of 2 assets, one is imported from Bridge while the other is imported from Fab. You can see that this has improved the displacement quality in fab:
