My friend died in lava when he was mining for netherite. He had a Netherite sword and two pickaxes (Silk touch and Fortune) That survived. They all had mending and Efficiency 4. Because he is a noob he died again but he got his stuff back. After mining a bit to get some xp back, he noticed he wasn't getting any xp (Meaning his pickaxes weren't mending) And ultimately one of them broke. He's still having the same problem, even with new pickaxes, and he doesn't even get xp from my blaze grinder. It's really, really frustrating. Also, He can get xp in the overworld (From Fishing) which makes it even weirder.