This announcement is a little overdue, but we have updated the CHARMM36 port for GROMACS to reflect the July 2022 version of the CHARMM toppar distribution. You can find the associated files at the same link above (MacKerell lab).
Hopefully we have rectified the few minor issues noted on the forum, and we have also greatly expanded the coverage of the force field to reflect essentially all of what CHARMM36 has to offer.
One quirk to make note of, as I have gotten questions on the forum and via email: In the case of an N-terminal MET residue in a polypeptide sequence, you MUST interactively choose the appropriate terminal patch. pdb2gmx tries to be smart and match by name but in this case, it causes an erroneous attempt to patch with a carbohydrate-specific patch.