It might be possible on some scenarios that Subpages are not being shown as expected.
Some Subpages or all of them are missing on some views.
Sometimes the PPM administrators configure display conditions of type (1=2) on subpages that they don’t want to appear anymore.
They would normally do that for testing purposes or to keep old versions of subpages that might need in the future.
This can cause problems and unexpected results on other display conditions on other subpages on the same view.