Sorry for the delayed reply. My new school term just started and was rather busy.
So far my major tackling point is probably the mesh and geometry, if what you mentioned about other solvers being able to produce the correct results, then I don’t think the simulation section or rather the setup of the boundary conditions should be wrong. I’ll be looking into each section to see if I can garner anything. No promise that I’ll be able to get anything useful so I’ll let you know if I do.
Interesting that the meshing did push the value up, however we’re still far away my a large margin so I still suspect it is some large oversight somewhere.
In the meantime if you are short on time, the runs you did in the other solvers will suffice as your validation case.