Dear Justin,
Unfortunately, A2AD was originally developed using the undocumented INFFNC() and INFARY() routines instead of the documented SYSFNC() and SYSARY() routines to avoid issues associated with functional dependencies. These undocumented routines are not available in some releases of MSC.ADAMS (e.g., the C++ solver). We know the problem cannot simply be eliminated by switching the INFFNC() and INFARY() calls to SYSFNC() and SYSARY() calls; this would lead to numerous alternative problems.
Instead, NREL is working with MSC to restructure A2AD in such a way as to only use documented routines and to improve the numerics of the solution.
Best regards,