Hi,
In my case it’s running on a Debian 8 environment, PHP 7.1, Apache 2.4 with a Nginx reverse proxy.
The _load function seems to set the WP_FAIL2BAN_PROXIES to false in my case (which it does when it can’t find a certain variable I believe, I don’t have the code in front of me right now).
I can run it through a debugger if you can’t find it but I’ll need some more time, let me know.
Thanks!