Chris , by hunting noise , do you mean a ‘Klerdunking’ noise as it fills? Sounds like a valve or pump being switched on and off rapidly ?
If it is , yours could be the classic ‘gunged’ up fill-hose . The hose gets blocked causing water to ‘back-up’ , bringing the pump on intermittently and causing low water levels. Low water levels means ‘no heat’ which means a wash/rinse cycle that doesn’t end.
Next time it does it , check the water level in the base. It should almost cover the whole base , just reaching the bottom edge of the salt lid.
Search on here for Neff/Bosch dishwashers not heating and there are some good explainations and pics showing the problem.