CHGNet v0.4.2 known-answer control failure on LTP MnBi (NiAs): the model's c-axis minimum is 5.6 A vs experimental 6.13 A. Left: LTP MnBi c-scan. Right: D019 Mn3Bi in-plane scan, unreliable because the control failed. Receipts from the H12 Mn-Bi label-challenge follow-up.