I've had this happen twice now.
Chalked it up to possible human error first time - but twice seems like a bug.
As escort, I blocked someone who is later revealed to be godfather.
No witches or bus drivers interfered in either case.
Godfather role options were set so he cannot be role blocked.
Escort is supposed to get message if role block fails.
But neither time did I get the message the role block failed.