YAPF clears the buffer on formatting

Describe the bug
I have set yapf as my default formatter in .vimrc and whenever I save a .py file, it clears the buffer. And if I change it to black or autopep8, it doesn't.

To Reproduce
Minimal vimrc:

Plug 'google/vim-maktaba'
Plug 'google/vim-codefmt'
Plug 'google/vim-glaive'

call plug#end()
call glaive#Install()

augroup autoformat_settings
    autocmd FileType bzl AutoFormatBuffer buildifier
    autocmd FileType c,cpp,proto,javascript,arduino AutoFormatBuffer clang-format
    autocmd FileType dart AutoFormatBuffer dartfmt
    autocmd FileType go AutoFormatBuffer gofmt
    autocmd FileType gn AutoFormatBuffer gn
    autocmd FileType html,css,sass,scss,less,json AutoFormatBuffer js-beautify
    autocmd FileType java AutoFormatBuffer google-java-format
    autocmd FileType python AutoFormatBuffer black
    autocmd FileType rust AutoFormatBuffer rustfmt
    autocmd FileType vue AutoFormatBuffer prettier
augroup END

OS (version)
Windows 10
NVIM v0.4.3 and vim-plug
yapf 0.30.0

Start with the AutoFormatBuffer path used by the Vim plugin and reproduce the report using YAPF 0.30.0 on Windows 10 with the provided minimal vimrc. Compare its behavior with the listed black and autopep8 formatters; done means saving a Python buffer preserves its contents while applying YAPF formatting.