AwesomeTTS no audio through web proxy

I realize I might get no support for this since I’m using an old version, but I have little choice because newer Anki versions don’t work on my Linux distro.

I’m using addon version 1.1.15. I cannot get voice previews because of my web proxy, Privoxy. Anki itself works fine through the proxy (it syncs), so I know that awesometts is the problem. When I click ‘Preview’, I get a popup that says

Cannot preview the input phrase with these settings.
Failed to parse

I have the http_proxy, HTTP_PROXY, and HTTPS_PROXY, and https_proxy environment variables set systemwide. I looked at the addon’s file, and a comment says

'The underlying library here already understands how to search the environment for proxy settings (e.g. HTTP_PROXY), so we do not need to do anything extra for that.

Any help is appreciated. I’m willing to do a bit of coding if necessary. and 8118 are the address and port for Privoxy.