Squid starts blocking websites, even though the blacklist is empty
I have installed Squid through the Package Manager on the following version of pfSense:
built on Mon Apr 11 18:10:34 CDT 2016
I haven't installed SquidGuard or anything else, but enabled Squid and ticked the Transparent Proxy checkbox. When I do this, websites such as TakeALot.com and Bacardi.com become blocked (www.takealot.com took too long to respond. ERR_CONNECTION_TIMED_OUT), while Facebook.com and Twitter.com remain accessible.
There is nothing on the blacklist, it's a clean configuration. Why are these websites being blocked?
I tried to add those two blocked ones to the whitelist, but it doesn't make a difference. I also tried to add Facebook.com to the blacklist, but it remains accessible.