LTE Link Monitor timing out

Hey All,

I'm running the LTE Link Monitor on nRF Connect 3.3.3. I'm connecting to my custom nR9160 Feather via the built in USB-to-Serial. I'm able to open the serial port in LTE Link Monitor. I hit the reset button and it shows the boot dialog. But when I tried to send commands, it doesn't respond.

While, if I try to connect via something like Cool Term I can issue AT commands without an issue.

I'm running on OSX 10.14.6