Browser Cache and Minify not enabling

Installed W3 Total Cache over the last few days – managed to get Page/Database/Object caches to work fine – along with CDN via Cloudfront.

However, I cannot enable Browser Cache, nor Minify.
The enable options are just greyed out.

I’ve run the compatibility report, and it shows the following:

Server Modules & Resources:

Plugin Version: 0.9.4.1
PHP Version: 5.5.21;
Web Server: Apache
FTP functions: Installed (required for Self-hosted (FTP) CDN support)
Multibyte String support: Installed (required for Rackspace Cloud Files support)
cURL extension: Installed (required for Amazon S3, Amazon CloudFront, Rackspace CloudFiles support)
zlib extension: Installed (required for compression support)
Opcode cache: Not installed
Memcache extension: Not installed
HTML Tidy extension: Not installed (required for HTML Tidy minifier suppport)
Mime type detection: Installed (Fileinfo) (required for CDN support)
Hash function: Installed (hash) (required for NetDNA / MaxCDN CDN purge support)
Safe mode: Off
Open basedir: On: /nfs:/tmp:/usr/local:/etc/apache2/gs-bin
zlib output compression: Off
set_time_limit: Available
mod_deflate: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_env: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_expires: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_headers: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_mime: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_rewrite: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_setenvif: Not detected (required for disk enhanced Page Cache and Browser Cache)
Additional Server Modules

New Relic
PHP version: Not supported: 5.5.21. Supported versions are 5.2.x, 5.3.x, 5.4.x.
Operating System: Supported
Web Server: Supported
WordPress Resources

/nfs/c01/h16/mnt/457/domains/XXX/html/.htaccess: OK
/nfs/c01/h16/mnt/457/domains/XXX/html/wp-content: OK
/nfs/c01/h16/mnt/457/domains/XXX/html/wp-content/uploads/sites/2/2015/05: OK
Fancy permalinks: /%postname%/
WP_CACHE define: Defined (true)
URL rewrite: Enabled
Network mode: Yes (subdir)

https://wordpress.org/plugins/w3-total-cache/