The "near collision" seems to have happened after both aircraft went around.
ZPJ instructed XGA to go around and position to south of the airfield.
ZPJ then missed their turn to final, went around and tracked to the same place they sent XGA.
Before XGA was instructed to go around I think things were OK, they were behind ZPJ in distance to the runway and more than 500' higher when ZPJ got the traffic alert. I assume the jet approach speed is greater than the GA8 so that should work. The XGA pilot was probably of the opinion that they had given way to the traffic in the circuit.