I don't want ANY calls coming through when my phone is in a focus mode/Do not Disturb

This has been driving me nuts for a while now.. But I cannot for the life of me figure out how to silence ALL calls while a focus mode is on. I don't even want my favorites to come through (unless they call 2x) Ugh this is so frustrating!! It used to work fine... Now I can't select "No one"... it's not even an option! Ridiculous. Unless I'm stupid and missing something.