| 1 | initial version |
I don't know how it used to work, but the way I understand it is that NumPy's matrix type is not a SageMath data type, so it doesn't support SageMath's latex rendering (in particular, it doesn't have a _latex_() method).
So just convert to a SageMath data type first:
sage: show(matrix(P))
$$\left(\begin{array}{rrrr} 0 & 0 & 20 & 20 \\ 0 & 20 & 20 & 0 \end{array}\right)$$
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