livedown stop not working

[hungrybirder]

Hello Shime

I'm using your vim-livedown and livedown to preview md files.
Recently I got a problem.
I found the command "livedown stop" doesn't stop the livedown process.

Some version infomation.
MacOS 10.13.3
Darwin mbp 17.4.0 Darwin Kernel Version 17.4.0
Node: v9.4.0
livedown: 2.1.1

This is my demo screenshot.

Thanks.

[hungrybirder]

Did I do sth wrong?
It still doesn't work.

Please help.