Usually this kind of artifacts come from a misaligned mesh, either the high-poly is shifted away or the low-poly, which result in gradients like this in the normal map.
If it's working in a new project but not in the current one, this could be related to different settings. I know you said the opposite, but can you just check again you didn't disable the "relative to bounding box" setting ? This could affect quite a bit the baking result.