I don't know if I'm having the same issue as the OP, but I'm noticing inconsistent blocking results with www.gambling.com. I'm still early in testing, but when I use that site to test the content blocking some user accounts will block it, some won't. I have no idea why it would be different for different users, all users should be blocked/allowed on an equal basis. Maybe it's just that site I'm using for testing, match.com seems to be blocked correctly on a consistent basis. Would the fact that www.gambling.com uses https have anything to do with this?
Not trying to hijack this thread, but I'm curious if my issue is the same as the OPs.