get stuck when load software.bin through /dev/ttyUSB1

I have raised a similar question #775 before, but this time it's quite a different case.
My working environment is VM Ubuntu 20.04, arty A7 35T board, symbiflow tools and the project I use is the `proj_template` under `proj` directory, which is one of the built-in default project.
When I run `make load`, it will be stuck at this command:
`/home/limx/CFU-Playground/soc/bin/litex_term --speed 1843200 --kernel /home/limx/CFU-Playground/proj/proj_template/build/software.bin /dev/ttyUSB1`
I have tried the following methods to solve it, but failed:
1. Reduce the UART_SPEED from the default 1843200 to 115200.
2. Press `Ctrl + C` or other keys on my keyboard. Press `Ctrl + C` twice quickly will end this command and other ways will cause nothing to happen.
3. Remove the whole `CFU-Playground` folder and rebuild everything by `git clone`.