Extreme Lightmap artifacts when imported objects have a rotation other than (0,0,0),Horrible Lightmap artifacts when placing an object at anything other than default rotation

I am having a baffling issue with HDRP 2019.4 lightmapper.

All objects imported into the scene (both .FBX and .blend) lightmap exactly as expected if their rotation is unchanged. If I rotate any object in the editor (other than built-in primitives) and then bake I am encountering horrible artifacts. See attached screenshots. The first shot the wall has been placed in the scene at default rotation and baked. The second it has been rotated 180 degrees and then baked again.

The horrible blocky artifacts are unaffected by scale in lightmap, resolution, samples, or generating UVs inside of unity. Altering or re-generating UVs in Blender will change the pattern of the artifacts but will not fix the issue.

Am I missing something, or is this truly a bug? ![alt text][1]