Mini Cooper S 2010 Coolant leak

my Mini Cooper S Clubman 2010 had a leak from the water pump area. I couldn’t tell where exactly from. I took it to my mechanic and when he saw the leak he thought it was the water pump or thermostat. Once he got there he found out the leak was coming from somewhere else he couldn’t see (upper). He removed couple other parts to find out and now the car is not leaking anymore even putting all the pressure to the pump. Any suggestions??
My mechanic doesn’t understand why is not leaking anymore and is reaching out to a Mini specialist.