Quick fix, not sure if it'll work when I have a robot to deploy to, but I changed the failonerror in the preverify.xml referenced by the build xml from true to false. This fixes the problem, the code builds okay, but I'm not exactly sure what I turned off, despite searching the documentation for Ant. Does this throw up any red flags for anyone, I'd hate to brick our cRIO...
Code:
<exec executable="@{preverify.executable}" failonerror="true">