Won’t let me list box weight

Hi, I’m close to ordering my first product batch. When I am selecting the box dimensions and weight, the weight option is not allowing me to input decimals. The box weighs 6.5kg (and it is asking for the weight in kg) however when I try and type 6.5 it gets deleted. Does anyone have any idea why this might be? Do I need to round up/down? Seems strange!

Thanks