It does not work.
Study what 16bit is and how the color values work - you’ll understand why photoshop doesn’t work after editing with it and comparing sampled values.
Also, No one in their right mind would leverage an image editor to deal with data. Particularly at a pipeline level.
And when you do “tests” at the very least you should take a scientific approach. Otherwise what’s the purpose?
As such:
What on earth is the purpose of testing a uniform file? At a minimum try a gradient from 0 to 1 across a file range which is larger than 65535 pixels…