Squidguard stops working with an invalid Client(source) IP address

[A Former User]

I use pfSense SquidGuard to allow a subset of LAN hosts to access certain internet domains. I've discovered that if an invalid IP address is entered in 'Groups ACL' > 'Client (source)', eg, 192.168.1.0, 192.168.1.256 or 192.168.3.999 SquidGuard allows all LAN hosts to access any internet domain. Just mentioning in case this is useful feedback - it certainly caught me out.