Datum system shifted/tilted

[[Ph...]]

We are currently creating a new template for ISO GPS-related dimensions.

Design intends:

Datum A is the mid plane of the 2 drafted planes A1 and A2

Datum B is the mid plane of the 2 drafted planes B1 and B2

Datum C is a plane normal to the axiy.

we have noticed that the actual fitted plane and the displayed coordinate are not perfectly aligned. There appears to be a slight angular difference as well as a small positional offset between them. computation mode ISO 1101 or geometry shown similar deviation but exactly the same.

Any idea how to fix it?