Do you use a module ? can you give a link to the module that you use, or give a schematic.
Could you make a photo of the wiring ?
Please show us your sketch.
These sensors are noisy and don't have massive resolution, that's the nature of hall-effect
current sensing. That particular sensor isn't supposed to have any significant hysteresis though, so it does
sound wrong. You've checked for a short between the current sensing terminals?