Ag, Rg not working

- [x] I have fzf 0.30.0 or above
- [x] I have read through https://github.com/junegunn/fzf.vim/blob/master/README.md
- [x] I have read through https://github.com/junegunn/fzf/blob/master/README-VIM.md
- [x] I have read through the manual page of fzf (`man fzf`)
- [x] I have searched through the existing issues

Hi! The ex commands that use the native file finder (`:Files`, `:FZF`) work for me, but all the ag/rg dependent ones do not.
Here's a quick example of what's on my system:
```
$ fzf --version
0.30.0 (2093667)

$ ag --version
ag version 2.2.0

Features:
+jit +lzma +zlib

$ rg --version
ripgrep 13.0.0
-SIMD -AVX (compiled)
+SIMD +AVX (runtime)

$ nvim --version
NVIM v0.8.1
Build type: Release
LuaJIT 2.1.0-beta3
Compiled by brew@Big-Sur

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

system vimrc file: "$VIM/sysinit.vim"
fall-back for $VIM: "/usr/local/Cellar/neovim/0.8.1/share/nvim"

Run :checkhealth for more info

$ vim --version
VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Nov 1 2021 21:44:09)
macOS version
Included patches: 1-2029, 3402, 3409, 3428, 3489
Compiled by root@apple.com
```

When I run ag/rg in zsh, they return the expected results. Running `!ag` and `!rg` in neovim/vim demonstrate that the binaries are accessible/run.

When run through `:Ag` or `:Rg`, I get no results (`0/0`) and the loading spinner spins indefinitely.

What are my next options for troubleshooting?