By selecting overlapping faces, no results were found, but when expanding the selection to include faces near the selected area, the desired selection effect was achieved?

[jiushi-ai]

Currently testing a problem:
When selecting self-intersecting + overlapping triangular faces on the model, and only selecting the overlapping option, no triangular faces are selected. However, when clicking "Extend Selected Faces," the extended faces appear.

Question: When only the overlapping option is selected and activated, and no faces are visible as selected, why do several faces appear when extending the selected faces?

[Grantim]

Hello!

The fact that "Expand Selection" works means that there is at least one present selected face, while it can be degenerated and not visible in 3d view. You can verify this by looking at information panel in the left bottom corner of the app window: