Hi Nicolas
Sorry for not following your support guidelines. I will remember in future 
OK, I'm not sure I fully understand. I would expect that if I set 4x4 then the first product category (since I have grouped by category) would always be filled with 4 items and then showing 4 rows (categories) and then pagination (16).
If not already, I would suggest for future Hikashop that it would list in this way 4x4 and then when you scroll page new columns and rows is auto loaded instead of pagination. Auto loading like you see en many feeds.
I will configure my many item to show what supported by now.
Thank you!
Regards,
Henrik