When I die, I lose all my things, and it also isn't on the ground where I died. Gravestone mods don't fix this. I think the mod in my pack that causes this is quark.

What modpack are you using? Is Quark Oddities installed? (If so, look for a Totem of Undying, little purple thing that floats around where you died. Punch that to get your stuff back.)

Haha, no, i wasnt using quark oddities. I'll be sure to add it into my modpack.

On the other question, i was using my own custom set of mods.