When standing inside a nether portal item in hand and offhand become invisible

I was playing on my survival world, and I jumped into my nether portal to go to the nether. While I was in the portal, and the animation of the pink swirls appeared on screen, the items in my hand and offhand became invisible, but no items were lost. If it is useful, th items I was holding was cobblestone in the main hand and arrows in the offhand