This problem is related to the fact that your readout rotation is 45 degrees, while actually TRestReadoutPlane::GetX,Y methods were only considering modules with 0, 90, 180, 270 degrees.
I have committed a quick fix in branch v2.2.11_dev that should solve that problem.
In any other scenario than 0, 90,180,270 we consider non-inversion. However, not sure about the conventions to consider in the re-definition of X and Y strip using rotations. Obvious for 90 degrees, ok. But what we do in intermediate steps? @nkx
On the other hand, I wonder if it is really necessary to have a 45 degrees rotated readout in IAXO-D0? @CMargalejo, @Elisa and @luzon