Why can Poisson's ratio be 77.93 for mp-672250?

Materials Project
1

mp-672250: Ti3Ga (hexagonal, P6/mmm, 191) (materialsproject.org)

Shear Modulus GV

24 GPa

Shear Modulus GR

-561 GPa

Shear Modulus GVRH

-268 GPa

Elastic Anisotropy

-5.16

Poisson’s Ratio

77.93

2

Another strange case:

mp-1001824: IrC (cubic, Fm-3m, 225) (materialsproject.org)

Poisson’s Ratio

-102.89

ELATE: Stiffness matrix is not definite positive, crystal is mechanically unstable.
No further analysis will be performed.