Hummingbird Browser Caching Error Message


I have activated browser caching in hummingbird and have the following error:

Browser Caching is not working properly:

    - Your server may not have the "expires" module enabled (mod_expires for Apache, ngx_http_headers_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.

Although this error is present I can see that expiry caching is being set properly on objects:

Cache-Control: max-age=2592000
Connection: keep-alive
Date: Thu, 15 Dec 2016 15:55:19 GMT
Etag: "1c0a6-543b184c97588"
<strong>Expires: Sat, 14 Jan 2017 15:55:19 GM</strong>T
Server: Apache/2.4.23 (Amazon) PHP/7.0.13
via: 1.1 (CloudFront)
x-amz-cf-id: eOn_oVp5uT1SXLyMOe1FcUFNpsgu2reGpQLDW_D1FnqjR-3A-kB2nQ==
x-cache: RefreshHit from cloudfront

Pingdom Website Speed test returns an A (100) for the site:

I have verified that mod_expires is loaded, that the .htaccess is properly configured.

Current plugins

Amazon Web Services
Query Strings Remover (would love this to be in hummingbird!)
WP Hummingbird
WP Offload S3 Lite ( for media images)
WPMU DEV Dashboard


(2) AWS EC2 t2.micro using AWS elastic filesystem
(1) AWS RDS t2.db.micro
(1) EC2 Load balancer w/ HTTPS endpoint
Cloudfront Distrubutions (CDN and *.APPLIKE)
* has 60s max/min ttl while setting up/testing
cdn has 3600 max/min ttl with versioning activated

Would like to understand how the UI is validating mod_expires exists and if the caching/elastic filesystem could be causing the issue with the plugin reporting an error on the dashboard.