Could you provide the nav mesh settings that you are using?
Could you provide any changes that you may have made to the template project?
Could you provide the command that is being used during runtime to show the nav mesh (I am using Show Navigation and I am not seeing the result that you are seeing)?
Im using the default settings, as you saw i just dragged a new Navmesh in from the Volumes tab without altering any settings except for its position and bounds.
No changes were made to the template project at all, it was a straight up new project.
The command that you are using is meant to only show the parts of the nav mesh that are currently active. This means what you are seeing is the intended functionality of this command. If you would like to see the complete nav mesh you could use the ‘~’ key to open the command prompt and you could then type in “Show Navigation”, this will show the whole nav mesh. I hope that this information helps.