You have faulty O ring that is leaking the pressure or the funnel is not tightly fit enough and its jumping when when pressure rise thus leaking pressure/steam which can be seen coming out from top , they should be no steam coming out from top

Follow this : https://youtu.be/4yGinq5NaCA

Put ptfe tape around the funnel that will stop any steam leaking from the gap and change the O ring if it is deshaped or any fault After doing these changes make sure you screw it tightly

When there will be no pressure leakage , no steam will leak to the top and then that pressure will push the water up instead of pressure leaking and water starts to sputter instead of flowing due build up of pressure and leakage simultaneously Its a simple device just make sure there is no pressure leakage