I am experiencing the same problem right now. Using Sitecore 8 Update 4 right now.
Below are a few more observations:
- I have a Template A as well, and I place presentation details on the shared layout as from doc.sitecore.net/.../versioned%20layouts, I understand it as you would want to put it on the shared layout
- In Template B, even though you see nothing in the layout, when you check the raw values, it has inherited the presentation details from Template A's shared layout and that's also populated in Template B's shared rendering field. I'm guessing this is a bug if it's not showing in the UI?
- If you now create a new page based on Template B, the presentation details DOES show for that new page.
- As soon as I add anything to the final layout for Template B, it wipes both shared and final rendering field clean.
- The page I created earlier will also have all presentation details wiped clean