I just re-read the original post and noticed that you mentioned that the sorting is off.
Well if it's off, I'm not sure what you expect Reposition() to do here. Of course it's not sorting them if the sorting is off.
The fact that they're added in a different order is just a platform discrepancy, a difference between editor and other platforms. If you want it to be in a specific order, turn sorting back on, and name them something like 001, 002, 003, etc.