For instance if you put your weigh boat down and tare it then remove it to add some sample the scale will often turn off before you have the chance to put the sample back on - this is true even if you dont remove the weight boat after taring and are adding a very small amount of powder, since you must be careful and take your time it will occasionally turn off on you;

this can also happen if you're getting really close to a specific amount (say 100mg) and just need to add 2mg more so you just tap your tweezers to add tiny bits of powder, if the amount you add is a bit under 1mg and doesn't cause the reading to change it will shut off on you. I would estimate the auto off to be about 30 seconds. What I do as a work around is remove the weigh boat after taring and tap the scale surface gently every little bit to keep it active, you can also hit the mode button, etc.