Short explanation is that the input voltage to the control circuit is 5V, and the relays are 12V.
I am feeding the 12v into the relays, and 5V into the control circuit along with the same power going to the ESP8266.
If I do not have the 12V power into the relays the control from the ESP works just fine, the LEDs on the relay module switch on and off as requested.
When I power up the relays with 12V the setup of my code succefully turns the relays on but they never go off.
I am feeding a LOW and they turn on, but a HIGH never seems to force them off.
Again, if I remove the 12V everything is hunky dory.
Is it possible this is because the output from the ESP is only 3.3V which somehow isn't enough to force the relays down?