Not all triops cysts hatch out after the first hydration, a certain percentage (depends on the species, but not much data is around on it) hatch after the second or even third hydration.
Also, the pH, temperature and overall hardness of the water can make very big differences too.
Usually for best results try to use distilled water or as close as possible (RO, de-ionised and rain water work very well too), but cant say that for certain for all species.
This is how triops have survived when things like dinosaurs went extinct - the cysts can last for even potentially hundreds of years at a time waiting just for the perfect conditions.
Also, some hatch out after different lengths of time (24 hours - 1 week it seems for
T.longicaudatus).
I'm currently struggling to get
Lepidurus apus cysts to hatch lol (messing around with ice and fans), so your not the only one struggling to get less studied species notostraca to hatch out
.
For best results try to find out the temperature conditions from times that you know they hatched out, and find out what type of water flooded their pools (rain water? flood water? from what river? how do I aim for that rivers water chemistry etc.).
You can store the mud to try again a different way if you like whenever you fancy giving it another shot
. Its possible theres quite a few cysts in there but they just haven't been triggered right, but then its possible theres none too lol.