VESC Mini 4.20 boots up inconsistently, any suggestions

I have 2 Flipsky Mini 4.20 VESC connected to two 10" hub motors. I have been able to connect and set up OK. When they are powered up at least 50% of the time, one vesc doesn't start properly. When it responds to a setRPM command it rub slowly in the opposite direction and never responses to any rpm increase commands, but it does stop if I send a setRPM(0). The opposite vesc starts and run properly. The next startup it will run OK. 

I am using two UART ports on a ESP32 to send the setRPM commands to each individual vesc.  Tried to reflash and setup again but that didn't seem to help. 
 

Any suggestions?
 

Thanks