If you get an opportunity can I get some information on your export to fbx settings? I tried to do a small edit with a shapekey and when I export to unity and replaced the prefab, the scale was majority off.
Not sure if my earlier reply actually sent, but I do have the export scale at 1.5
If you have any continuing problems with the export, I will add the Export preset to the available files.
Can I get an export preset, just so I don't mess up anything in the future