UART Comms Issue

I’m using a v3.6 56 V oDrive with firmware as shipped. I’m talking to it with an ESP8266 over the UART. I can send cmds and oDrive responds correctly, but I’m having problems with replies from oDriive. I get ‘unknown command’ in response to request ‘r vbus_voltage\n’. I’ve checked the rest of the oDrive reply after ‘\n’ and I there’s ‘invalid property’ tagged on the end. I’d be grateful for any ideas!