Block all rule disappearing on refresh

I’m trying to add a “block all” rule to the very end of my Global Rules section. Why does it keep disappearing when I refresh the firewall rules window? My other rules don’t disappear…

“Block IP In/Out from MAC Any to MAC Any where protocol is Any”

What do you mean with refreshing the firewall rules window? Can you describe step by step what you do? Do you close the window with OK? If not the change won’t stick.