When we do a section under an iModel review.
On the element being section, the section area display no edge, making a flat view and harder to distinguish element.
Options should be provided to allow better sense of cut
Find the option, however the display of the cut area generate extra line
The Render Mode can impact what is displayed you might want to change that under the presentation mode at the bottom of the model. Also turning on Visible edges and/or Hidden edges under the View attributes can help view these elements.