Visiting /api/rest on my store results in a 404 error page - why?
LoyaltyLion requires API access to your Magento store in order to function correctly.
If we can't access your API, the most likely explanation is a misconfigured .htaccess directing API requests to the wrong part of Magento internals.
A correct .htaccess has a rewrite rule near the beginning which looks like this:
RewriteRule ^index\.php$ - [L]
RewriteRule ^api/rest api.php?type=rest [QSA,L]