When I try and enable compression I get the following error:

gzip is not working properly:
- Your server may not have the "deflate" module enabled (mod_deflate for Apache, ngx_http_gzip_module for NGINX)
- Another plugin may be interfering with the configuration
If re-checking and restarting does not resolve, please check with your host or open a support ticket with us.

I have deactivated a lot of plugins with no change. I have other sites using Hummingbird's compression just fine with the same hosting. I have granted you access if you could please have a look?