Tried two Illustrator versions, 2018 and 2020. The issue is, when I export as PSD it exports without layers as flat image. https://drive.google.com/drive/folders/1Ufh9mebCLki1VDJ7RNmp15-pur3jHMpD?usp=sharing
Tried to google, found some workarounds, but all of them not working. Used Ungroup all and Release all layers options but still no luck. Also tried to do single files for each artboard, example attached 1.ai file is still not working, flatten when exported.