CNCJS Basic troubleshooting question

I’ve got a Burly with a newly flashed Marlin 2.0.7 board, and if I set the baud rate to 250k I can get CNCJS to talk to it:

CNCjs 1.9.22 [Marlin]
Connected to /dev/tty.usbserial-AL00WZH5 with a baud rate of 250000
echo:start
Marlin 506D 2.0.7
echo: Last Updated: 2020-09-29 | Author: (V1 Engineering, Ryan, 506D)
echo:Compiled: Oct 19 2020
echo: Free Memory: 3466  PlannerBufferBytes: 1472
echo:V81 stored settings retrieved (641 bytes; crc 45999)
> G91
>

However, nothing I do either in the keypad on the right of the UI or through the console (e.g. the G91 above) seems to result in a response, either mechanical or otherwise (no OK back).

What am I missing? I’m soooo close!

Turns out the answer was I’d enabled hardware flow control, which was a bad idea. Now works.