When Pro/E does not display the edges you would expect to see in an ISO view, components are interfering with each other and Pro/E simply does not know how to display edges in views. Unfortunately, the only way to fix it is to have non-interfering components, which may not be the design intent.
Aftering wasting several hours last week on this same problem I found the solution here.
Shocking to see that such an important bug still has not been resolved in WF4 M080, 10 years(!) after it has been known to exist
So there is -NO- way for me to display the drawing views of this assembly and the upper assemblies exactly the way I want them to. (/sarcasm on) Thank you PTC! (/sarcasm off.
I'm glad at least there is this great forum where you can always get real help and in most cases a decent solution to your problem