I upgraded from Mac OS X 10.10 (Yosemite) and Mac OS X 10.11 (El Capitan) and my Infinity pedal stopped working.
I diagnosed it to a USB issue. If I plug the pedal directly into my MacBook Pro or my Mac Pro, it is immediately detected.
If I plug it into a USB hub, it is not, even if it is a powered hub, and even if that powered hub has no other devices attached.
Using "About this Mac" -> "System Report" shows that the Mac sees the device in either case, so I'm pretty sure this is a software change.
I have another Mac transcription program that works with the same pedal whether directly connected or on a hub, so I'm pretty sure that for some reason the Express Scribe program is only scanning the top-level of USB devices, and if it doesn't see the pedal, it gives up.
I hope this helps.
--mdc