Loot problem

Loot disappearing before I can pick it up, my sister is having the same problem in poe2

Probably not an issue if you see the items initially, but also check the "Toggle Highlighting" option in Options - Input tab for Keyboard/Mouse. By default this is (Z), which I find very easy to hit by accident with my keybind layout.

In Path of Exile 2, if your sister is playing with a controller the "Toggle Item Visibility" setting (analogous to Z to Toggle Highlighting) has been defaulted to the second control set as (LT + DPAD RIGHT). This has caused confusion for a lot of POE2 players. This is not defaulted in POE1.