My loot is being deleted when i go to pick it up.

This happens occasionally; it usually happens when i open a chest in Alva temples.

However, today it happened in Inscribed Ultimatum, I offered Ngamahu's flame abyssal axe. It dropped a void battery, when i hover over and go to pick it up, its instantly deleted from the game. And no, its not covered by a filter. Even if i turn all filters off its gone.

My best guess (and it isn't a very good one) is that it is somehow to do with a loot filter. Next time it happens, could you visually scan the ground where it dropped and see if you can pick out the sprite of the object? If you can see it, then that would confirm that it is some kind of UI glitch and that the item still exists server-side. On the other hand, if you can see enough clear ground to confirm it definitely isn't there, then that at the very least means that both the environmental drawing portion and the text-object interface portions of your unit interface both agree that the item isn't there.