Bug (?) in OptimTraj wrapper for GPOPS?

I'm having some trouble getting the OptimTraj gpops method to work on my problem in certain cases. Do you know what might be causing the error below? I think this error may be related to how OptimTraj wraps GPOPS-II, because whenever I use GPOPS-II independently from OptimTraj on my optimal control problem, I never get this error.

| |
| Finding Solution on Mesh 2 |
|___________________________________________________________________|
Computing Radau Points, Integration Weights, and Integration Matrix
Creating Bounds For Nonlinear Program
Creating Guess For Nonlinear Program
Error using griddedInterpolant
Interpolation requires at least two sample points in each dimension.

Error in interp1 (line 161)
F = griddedInterpolant(X,V,method);

Error in gpopsGuessRPMI

Error in gpopsSolveRPMI

Error in gpopsMeshShell

Error in gpops2

Error in gpopsWrapper (line 84)
output = gpops2(setup);

Error in optimTraj (line 190)
soln(iter) = gpopsWrapper(P);

Error in invoke_OptimTraj (line 176)
soln = optimTraj(problem);

Start by reproducing the failure with the missing optimal-control problem and inspect the call path from optimTraj through gpopsWrapper at line 84 into gpops2 and gpopsGuessRPMI. Trace which input reaches interp1 with fewer than two sample points, then verify the fix against the reported Mesh 2 failure and a regression case.