EZO RTD temp sensor fails calibration in one PC, but works in a different PC

So I am currently trying to send commands to my EZO RTD temp. sensors through serial communication. I am able to turn on/off the LED's on the sensors (L,0/L,1), but whenever I perform any other command (such as a calibration [Cal,n]), my sensors fail to receive data (response code: 2).

HOWEVER, when I upload my code on my other PC, it will upload just fine, and will perform any command that is inputted. This is very confusing to me, as my code was working just fine before hand on both PC's. My initial assumption was that it was a USB issue, however, I am unsure.

It is worth noting that I am using an Arduino Mega2560 as a master, with multiple EZO RTD sensors as slave, so I am in I2C mode. I am in the process of converting these sensors into a LabVIEW code, however, I still use Arduino code to calibrate.

I have tried sending an exact copy of the code on the working PC to my other PC, however, it still gives me a response code of 2.

Both computers in the device manager have the same port settings? Both IDEs are set the same for port baud rate? Something is different and it sounds like in the communications.

Ron