How was your sample Mn metal prepared? Do you have verification that it is metallic?
When you say "from metal reference foils measured at the beamline.", I wonder if that might be the same kind of
"reference foil set" in the wooden jewelry box that we have at our beamline. Most of these are very good, while some (Pb) degrade over time. Ours has one labeled "Mn" which is obviously a black powder, probably sintered. I've never tried to analyze that as BCC Mn and assumed it was stable-ish, but not metallic. But maybe someone else has tried that.
--Matt