I tried optimizing the geometry of the attached structure using GFN-FF, which is optimized at the GFN2-xTB level and looks reasonable to me. The optimization trajectory shows very erratic behavior (rearranges one N-H bond and inserts it into a C-N bond). I would like to emphasize that optimizing the structure with GFN2-xTB is not a prerequisite for this behavior as it also happens without it at various alternative, but in my view reasonable, starting structures. However, I wanted to make sure that the starting structure has no obvious problem I am missing.
gfnff.tar.gz