Creating a condition for hour of the day

I was asked today to create a Flow to auto reply to Yammer posts in a group, but only after normal business hours. There is an existing autoreply template so my thought was to keep the first condition that checks for a new post with no replies and then nest a second condition that checks the hour of the day like 

@less(utcnow(‘H'),11) for example.

I figured if that worked I could get fancy later and add in a delay so a human replying quickly could defeat the autoreply.

But I cannot seem to get that second condition to work, it fails with the error ExpressionEvaluationFailed no matter how I approach it.