If that doesnt work, maybe you got some bad Triops eggs???
Q: I’ve got 8 (out of a hatching of 10) Triops longicaudatus living in a shallow plastic tank which holds less than 2 litres. They’re currently about 24 days old and all 8 are egg-bearing. I feed them quite a lot and they always have aquatic plants to munch on, which I think has kept cannibalism to a minimum.