block sites only worked for 1 day

Dear Netgear Expert/Support

I just got a C6300v2, activated for xfinity. it works fine. but I notice that the block function only worked the first day, 

After I added in the keyword, I think I checked the function and it worked. but when I checked it second, seems to me that none of the keyword in the block list working. is there anything wrong? will the xfinity will control/change the behavior of the modem? 

This is a key feature to use this modem at home. please advise. I need make decision to keep it or return to Amazon. 

Appreciate your help. 

David