The system cannot find the specified path when calling :PlugClean or :PlugInstall

When I run commands such as `:PlugClean`, I get an error saying
> The system cannot find the specified path

However, if I copy and paste the exact path into the explorer, the directory exists


It also happens with `:PlugInstall`


Running `:PlugStatus` outputs the following


------------------------------

```
:version
NVIM v0.4.4
Build type: RelWithDebInfo
LuaJIT 2.0.5
Compilation: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x64/cl.exe /DWIN32 /D_WINDOWS /W3 /MD /Zi /O2 /Ob1 /DNDEBUG -DMIN_LOG_LEVEL=3 /W3 -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_DEPRECATE -DWIN32 -D_WIN32_WINNT=0x0600 -DINCLUDE_GENERATED_DECLARATIONS -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -IC:/projects/neovim/build/config -IC:/projects/neovim/src -IC:/projects/nvim-deps/usr/include -IC:/projects/neovim/build/src/nvim/auto -IC:/projects/neovim/build/include
Compiled by appveyor@APPVYR-WIN

Features: -acl +iconv +tui
See ":help feature-compile"

system vimrc file: "$VIM\sysinit.vim"
fall-back for $VIM: "C:/Program Files/nvim/share/nvim"

Run :checkhealth for more info
```

- Type:
- [ ] Bug
- [ ] Enhancement
- [ ] Feature Request
- [x] Question
- OS:
- [ ] All/Other
- [ ] Linux
- [ ] OS X
- [x] Windows
- Vim:
- [ ] Terminal Vim
- [ ] GVim
- [x] Neovim