Earlier today we ran into the problem that when creating a section in one plan view, it would not be visible in another plan view, not even as a hidden object.

Turns out that Revit seems to assume that when you create a section in a view with a certain scale (1:100 for example), that this section should only be represented in views with a scale smaller than that.

In other words: Revit automatically sets the Hide at scales coarser than - property to whatever scale the view is you created the section in:

And if you are working in views with different scales, this can lead to a lot of confusion.

So, next time you are missing a section symbol in a plan view, check this setting first.