Since you have a Proxy then you probably need to add the IP address that you see in the REMOTE_ADDR Security Log entry field. Do the steps below.
1. Add the IP Address that you see in the REMOTE_ADDR Security Log entry field in the Plugin Firewall Additional Whitelist Tools > Whitelist by Hostname (domain name) and IP Address tool.
2. Click the Save Whitelist Data button.
3. Click the Create Firewall Master File button.
4. Select the Plugin Firewall BulletProof Mode Radio button.
5. Click the Activate|Deactivate button to activate the Plugin Firewall.
If the problem is still occurring then do these steps below.
1. Go to the Plugin Firewall page.
2. Select the Deactivate Plugin Firewall BulletProof Radio button and click the Activate|Deactivate button.
3. Delete all of your Plugin Firewall whitelist rules out of the Plugins
Script|File Whitelist Text Area.
4. Click the Save Whitelist Data button.
5. Click the Create Firewall Master File button.
6. Select the Plugin Firewall BulletProof Mode Radio button.
7. Click the Activate|Deactivate button to activate the Plugin Firewall.
8. Turn on AutoPilot Mode to 1 minute.
9. Check your site using http://boomproxy.com/ and click on all main website pages: contact form page, home page, login page, etc.
10. Recheck the Plugins Script|File Whitelist Text Area and you should see new Plugin Firewall whitelist rules have been created.