Review on WOWOHE Portable Digital Pocket Food Scale - 500g Capacity for Kitchen, Small Mini Cooking Scale - Ideal for Lab, Gram Measuring Scale by Dawn Sherman

I use it to weigh out a small amount of drinks and soda ingredients. It gives reproducible results for plastic cups, when I weigh them for the first time, when I tare and start adding ingredients I find the scale is stuck for lack of a better description until I add a large amount and then suddenly I realize that summing them up all the smaller additions and flights I wanted, for example I want to weigh 0.42g. I have 0.38g, I add what should be about 0.01g, then more, then more, then more, then more, no change, in fact it can be lower, and then suddenly it becomes more than 0, 42g I've found that if the reading doesn't change, the reading may change if I pick it up and put it back on. However, the drifting of the measured values becomes annoying. How can I be sure I'm filling everything correctly when I take it out, empty the container, clean it and put it back on and it starts to weigh less or more than it did before?