It always works perfectly for me with double page. Unfortunately, I don't understand what you mean by "fine-minimum page fold". If this crease appears after printing, then the machine is not calibrated correctly, if this is the case, I would complain immediately. Attention, warranty length!

I've never noticed anything like that before - I've been in my home office for 5 months and use it quite a lot as a club and family press. And mostly double-sided, partly because of environmental protection.