When you say you bled the cooling system, you did bleed it at all three bleed points?
However your problem may just be that the flush washed away the rust, dirt and stubborn under stains holding hands that was keeping the cooling system together.
In fact there may’ve been some miracle cooling system muck put in the system to “fix “ a leaking system and the flushing agent has washed this shit away.
Once you find the problem fix it properly….. no amount of miracle elixir snake oil will ever give a permanent and satisfactory result.
The best way to tell is do a pressure test, and getting under and all about the cooling system whilst it’s under pressure.
To do this you need a cooling system pressure test kit such as this one:
One of these
You pump up the pressure and you can safely search for the leak without the hazard of scalding yourself with boiling water or worrying about damaging the engine.
Pity that you’re on the other side of the Tasman sea and not in Melbourne otherwise I’d be able to pop over and test it for you.