There seems to be a problem with my radiator system as the engine comes really close to overheating before I cut it off, my temperature gauge shows zero meaning cold and the radiator itself is cold, the coolant flowing into the waterpump is cold but it doesn't seem to be circulating. Thermostat is working and there are no blockages, the water pump is also turning so what else could cause this?

I changed coolant recently but there aren't any blockages and no leaks either, I have checked my thermostat and it is fine I am going to try my radiator itself now