serial_test | Allows for the creation of serialised Rust tests | Unit Testing library

I am trying to receive some data from a microcontroller connected to a windows PC through USB. I am doing this with the .net SerialPort functionality as you can see in my code below. I know the sleep is not very elegant but this is just my test code since I cannot get this to work.

Basically I have an Arduino sending some data which I can receive with the Arduino Serial Monitor, my c# program only outputs emtpy lines though, and the receive buffer is always emtpy. (the exact code you see here will output a zero and an emtpy line every second, even though a random number is sent every 200ms) I already confirmed the baudrate is correct on both ends, I also switched over to a raspberry pi pico which had the same result. I would really appreciate it if someone could help out here, as far as google is aware I must be the first one to run into this :D