Hi,
Your "default" object has scale of 1000 and is rotated by -90°, 90°.
Often times this is the culprit for such issues, conflicts within hierarchy & mograph using 3rd party renderers.
1. Fix Scale by resetting it to 1
Tool: Reset Scale w/ Compensate Points (checkbox on)
2. Fix Orientation by setting Axys to 0°
Tool: Enable Axis (shortcut L). Set P, B to 0° in Coordinates window (NOT in Attributes/Coordinates!)
Further on you could also center Nulls to geometry of Parents... or simply Connect Objects (children) into one - that way you will always prevent any further occurrence of such issues & have well organized scene.