[TextMesh Pro] When setting TMP LiberationSans SDF Material Softness value bellow -0.017 text disappears at Dilate ~0.6 or less

To reproduce:
1) Open attached project
2) Open Simple.unity scene
3) Select Simple game Object
4) Go to the material. Set the Softness to -0.018 and Dilate to 0.591

Expected Result: The text is still visible
Actual result: The text is not visible

Alternatively, the material should check for valid values and get the necessary information

Note: There's a gif attached which shows the problem.

Reproduced on Textmesh pro 1.0.21, 1.3.0, 1.4.0, 2.0.0