Comment (by Samuel Cupp):

It’s been a while since I looked at it, but I think it should be in HydroBase_PostStep after HydroBase_Con2Prim. update_Tmunu is a parameter, not something in the scheduler. If you don’t want IllinoisGRMHD to ever set Tmunu, then you need to set that to no in the parfile. It defaults to yes. I didn’t get nans with update_Tmunu=yes, but I did with update_Tmunu=no.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2497/illinoisgrmhd-is-incompatible-with-setting