The list of sides you can set on a product photo now offers front and back only.
Those two are what image generation works with. The list previously also offered side, top, bottom and other, but nothing further along the pipeline could act on them — a photo marked one of those was sent for generation with no usable indication of how the product should be oriented, and the result was whatever the generator decided on its own.
Setting a side now always means something. A photo marked front is generated as a front view, one marked back as a back view.
Photos that carry no side are unaffected and do not need one: the generator reproduces the orientation it sees in the source photo, exactly as before. A small number of photos previously carried a side outside the two — almost always guessed automatically during analysis rather than chosen by anyone — and those have been reset to no side, so they now follow the same rule. Nothing marked front or back has changed.