Correction: Your sentence passes. The antecedent for "it" in that sentence is the word "duty". The words "off duty" were not hyphenated, so I guess "it" could refer to "duty". My mistake.
For the record, I really don't care about the use of pronouns or hyphenation in the posts on this forum. Just having fun because I know you're the grammar cop here.
I don't think I'm a "cop", but it is always interesting to see how people express themselves on a thread about education. ;)