Netherite swords disappear when player tries to pick them up

I tried this only in Creative mode for I have no enough nethrite ingot yet in the survival.

Once I have thrown some Netherite swords on the ground with the same enchantment, then I tried to pick them up. It looks like they have all been in my inventory but when I go for a check it showed only 1 of them (which actually should be 6 logically)

They were not piling up, and my inventory was with only 1 blank left. Hence the extra sword were not intended to be "absorbed". But they all did and disappear.