FF Scala Sans Pro bold web font missing fi ligature?

[riferguson]

If I create a web typekit containing FF Scala Sans Pro normal and bold (weights 400 and 700, respectively), fi ligatures appear as expected in the normal weight but *not* in the bold weight.

See attached images from the same web page.

If I switch that same page to a webfont version of FF Scala Sans Pro from FontFont, both ligatures work.

What am I missing? Is the Typekit version broken?