Why is my 1x1 being used in Stories?
Kitchn uses a position-based logic to map assets to their relevant placements.
If you don't change the default Placement Customization Settings, the first assets will be uploaded to all feed placements, whereas the second asset will be uploaded to all Stories and Reels placements.
How to fix:
9x16 should be position 2
1x1 should be position 1
Switch asset positions.