(I am running V5R18, I forgot to mention it. Just in case it might be relevant. I was used to V5R16 maybe some things changed that I did not notice.)
You're right. When I hover the mouse over any cylindrical geometry in the assembly mode (let's say, for instance, I have two cylinders and I want to create a coincidence constraint to line them up) it does not pre-highlight its axis (nor the faces). I've now learned where to click to make it pick the axis or the face but still I would like to know why it doesn't show me the axis and why it doesn't pre-highlight the faces.
I've trying changing the pre-higlighting options in the
Tools > Options > General > Display > Navigation menu as you said, but no combination seems to be a solution to my problem.
Thanks again for your answer. And sorry if my english is confusing, it's not as good as I would like it to be (yet!).