When im putting something with Portal-NS (ID 68) by selecting this in inventory, it felt wrong, it was invisible at first, thinking the Order is 0, but when i toggled the ID 68 as a message block and checked by typing /mb, it didn't show up here, There is the Proof:

Then when i decided to remove ID (68) and check the inventory, it stayed there and remained hidden

And when i copyed the ID 67 to ID 68, it didn't appear, so Can You Tell what happened?

You can comment below, because i'm waiting

It looks like you may have mistyped the ID when toggling it as a message block. If a block isn't appearing in the menu make sure to reset its order by setting its order to its ID