I was fighting wither skeletons to collect skulls for beacons when I died being withered away, I couldn't get back because it was hard so I asked my friend who was the world owner to set it to peaceful so I could retrieve my items, everything except my full set of enchanted netherite armor and my enchanted netherite sword was there, it was't floating in lava as I went down to check with fire resistance. Why does this happen instead of dropping all the items when it's set to peaceful?

I was fighting wither skeletons to collect skulls for beacons when I died being withered away, I couldn't get back because it was hard so I asked my friend who was the world owner to set it to peaceful so I could retrieve my items.
Everything except my full set of enchanted Netherite armor and my enchanted Netherite sword was there, it was't floating in lava as I went down to check with fire resistance. 

Why does this happen instead of dropping all the items when the world is set to peaceful?