(Using Blender 3.6.5)
The answer is similar to this other post: Array Modifier does not work as expected. The issue is about unapplied transformations.
The consequences of applying transformations are that:
- The object is rotated, then its local axes are aligned with the world axes.
- The object is scaled, then its scaling factors are reset to 1. Its dimensions are updated.
- The object origin is set to the world origin, but its vertices are not moved.
A more extensive explanation is provided here: Why is it important to apply transformation to an objects data?
NB: In the following figures, from the original Blender file, the Empty object is slightly shifted along X axis to see copies when the Array/Count is greater than 1.
Before applying the transformations:

After applying the transformations:
