I got this on a freepbx 14 server just now and found the fix to be the same. In the Firewall module go to Advanced, Advanced Settings, and scroll down to Intrusion Detection Sync Firewall setting and click Enabled instead of Legacy. It changes how the whitelist works a bit.
Here;s where I found it, there is more discussion there
Fail2ban and fwconsole - FreePBX / Security - FreePBX Community Forums