I just heard back from the Development Team.
Here are their comments:
"Object does not render in the Modern viewport, which is a strong suggestion that there is something wrong with the geometry specification."
For example, the edge 6->2 is parallel the z-axis, and edge 2->1 is parallel the x-axis, but edge 1 ->5 is not in an XZ plane. The best option for you is to adjust vertices 6 and 7, and check with Modern viewport.
I haven't had the chance to test this myself but I will suggest you to try these recommendations. We also think that the geometry (or one or more of its facets) should be surrounded by a red box to indicate that a certain geometry (or facets) are problematic. This will help customers identify any issue with the geometry. I will submit this feature request.
Let me know if you have any questions.