Red Garbled Text in Console

Hi, I was wondering if this behavior is expected.
When I set SIM_UART_LOSS, red garbled text appears in the console.

Additionally, when the value is small (e.g., 0.1), only the red garbled text appears(Figure 1 below). However, when it’s larger (e.g., 5.47), the GCS connection shows “timeout setting SIM_UART_LOSS to 5.470000”.(Figure 2 below) This seems like SIM_UART_LOSS should not have been successfully set, yet the issue still occurs.

I’m using ArduCopter-SITL v4.7.0.
FYI, here is the link explaining how SIM_UART_LOSS is implemented.