Hello Moco users, We've recently found a few critical bugs regarding muscle wrapping with the DeGrooteFregly2016Muscle in Moco. These bugs include wrapping surfaces not being copied into DeGrooteFregly2016Muscles when using ModOpReplaceMusclesWithDeGrooteFregly2016 and wrapping surfaces not supporting parallelism in MocoCasADiSolver. Please refer to this SimTK forum post for full details: https://simtk.org/plugins/phpBB/viewtopicPhpbb.php?f=1815&t=12792&p=0&start=... . We are working on fixes for these issues now, and they will be included in the next release of Moco (which will be included with the OpenSim 4.2 release). Best, -Nick -- *Nicholas A. Bianco* Neuromuscular Biomechanics Lab <http://nmbl.stanford.edu/people/nick-bianco/>|Stanford PhD Candidate (772) 284-0354