EDIT:
From the info on the JCM website it looks like there is one newer software release called ID-003 ver 3.83, released in Oct 2013, for your WBA-13 after the software version 3.80 you currently have. But the reason for the release didn't affect acceptance of $10 bills so updating the software probably wouldn't help. The last software improvement to $10 acceptance happened at ver 3.75, so your ver 3.80 already has that improvement. (I didn't see a ver 3.93 that dhellis saw, maybe I missed it or his comment has a typo?)
Your WBA-13 has 4-way acceptance, you can insert a bill face-up or face-down, either end inserted first. If your WBA accepts all $20 and other bills ok, maybe it is just a quirk about the $10. From what I've seen most people play by using $20 or $100 bills and either $1 or $5 for something smaller, so not being able to use a $10 isn't a big problem.
The SIS document for the ver 3.83 is below.