Mangoh Red HL7800 Strange AT commands

Hello,
I am trying to send AT commands to my HL7800 module on my mangoh red board, but it is acting strange…

I have a TTL cable connected from my computer to pin 8 and pin 10, and USB going into CN305, GNSS and Cellular antennas and a LiPo connected.

If I send AT, some times it responds with OK, and some times it responds with ERROR or some strange characters.

AT
OK

AT
IU

AT
ERROR

AT
]

AT
OK

My settings are 115200,N,8,1 with flow control turned off.

Lastly, If I connect the UART -> RS232 module into CN305, communicaitons work fine. Problems are only when using UART on pin 8/10.

Thoughts?

What version of mangoh red? Note we only support mangoh red with HL78 on DV6 using the IoT card that is present inside the right sku.
https://www.digikey.ca/product-detail/en/talon-communications-inc/MANGOHRED-HL7800/1788-1026-ND/9953591