This is a known issue that will be fixed in the VEX Support Package's monthly release of October (on Oct 11, 2017). You could reinstall the support package after that date to obtain the updated version in either Simulink R2017a or R2017b release.
However, if you are looking for a workaround immediately, please go to the following link for more information: http://forums.bestinc.org/post/important-download-the-fix-to-the-arcade-module-block-in-vex-simulink-r2017a-library-9310019?pid=1300192360
If you need more assistance on this matter, please contact us at email@example.com.
MathWorks Student Competition Team.