Is the water level in the tank filling to the proper level then shutting off properly?
Is the water in the tank then draining into the bowl through a leaking flush valve and when it drains down enough the fill valve turns on and refills the tank to the proper level.
This can be verified by die testing with food coloring, if the color gets into the bowl without flushing it is leaking!
In which case you need to service the flush valve.
Here is the instruction manual.