Write to RTT using pylink-square library

Question

Using this example of the pylink git repo, I am able to send commands to my Nordic Board and control it over the RTT. Now, I derived my own little python script from this example, where I want to send one command:

def write_rtt():
    jlk = jlink.JLink()
    jlk.open()
    jlk.set_tif(pylink.enums.JLinkInterfaces.SWD)
    jlk.connect("nrf52832_xxaa")
    print(jlk.target_connected())
    jlk.rtt_start()
    cmd = 'send beep beep_start_req d=05.00.C8.00.C8.00'
    bytecmd = list(bytearray(cmd, encoding="utf-8") + b"\x0A\x00")
    jlk.rtt_write(0, bytecmd)

if __name__ == '__main__':
    write_rtt()

The target_connected() command returns True, but the command doesn't achieve the effect that it does if I enter it using the example.

What am I doing wrong? I basically just copied the code of the example's write_rtt function. What am I missing?