When you build an object in edit mode, as soon as you get back in Object mode all the edges disappear.
Example:
I personally like to see the edges while I’m building my objects. To enable that all you have to do is:
Then change the navigation to “Properties”:
Then choose the object you want to display the edges for. Note that this is done on an individual object basis.
Scroll down to the Viewport Display section and check the “wireframe” option:
That’s it.. Do that for every object and you should get something like this:
The basics of basics in Blender 2.8 