I have a parent project that consists entirely of placeholders to child projects. The parent project has no content. When I generate the responsive HTML with Indigo I noticed that when you perform a search and select a file from the search results, the file displays, but the breadcrumbs do not. Neither does the TOC expand to show where this file is in the TOC.
I generated the output on a single project with content and with no toc placeholders to other projects, and the navigation worked correctly.
I am on 2019.0.12, this is a new project, not an upgraded project.